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Articles 841 - 870 of 892

Full-Text Articles in Pharmacy and Pharmaceutical Sciences

Isolation Of Current Components And Partial Reaction Cycles In The Glial Glutamate Transporter Eaat2, Thomas S. Otis, Michael Kavanaugh Jan 2000

Isolation Of Current Components And Partial Reaction Cycles In The Glial Glutamate Transporter Eaat2, Thomas S. Otis, Michael Kavanaugh

Biomedical and Pharmaceutical Sciences Faculty Publications

The kinetic properties of the excitatory amino acid transporter EAAT2 were studied using rapid applications of l-glutamate to outside-out patches excised from transfected human embryonic kidney 293 cells. In the presence of the highly permeant anion SCN−, pulses of glutamate rapidly activated transient anion channel currents mediated by the transporter. In the presence of the impermeant anion gluconate, glutamate pulses activated smaller currents predicted to result from stoichiometric flux of cotransported ions. Both anion and stoichiometric currents displayed similar kinetics, suggesting that anion channel gating and stoichiometric charge movements are linked to early transitions in the transport cycle. …

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Pentameric Assembly Of A Neuronal Glutamate Transporter, Sepehr Eskandari, Michael Kreman, Michael Kavanaugh, Ernest M. Wright, Guido A. Zampighi Jan 2000

Pentameric Assembly Of A Neuronal Glutamate Transporter, Sepehr Eskandari, Michael Kreman, Michael Kavanaugh, Ernest M. Wright, Guido A. Zampighi

Biomedical and Pharmaceutical Sciences Faculty Publications

Freeze-fracture electron microscopy was used to study the structure of a human neuronal glutamate transporter (EAAT3). EAAT3 was expressed in Xenopus laevis oocytes, and its function was correlated with the total number of transporters in the plasma membrane of the same cells. Function was assayed as the maximum charge moved in response to a series of transmembrane voltage pulses. The number of transporters in the plasma membrane was determined from the density of a distinct 10-nm freeze-fracture particle, which appeared in the protoplasmic face only after EAAT3 expression. The linear correlation between EAAT3 maximum carrier-mediated charge and the total number …

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Arginine 447 Plays A Pivotal Role In Substrate Interactions In A Neuronal Glutamate Transporter, Annie Bendahan, Ayelet Armon, Navid Madani, Michael Kavanaugh, Baruch I. Kanner Jan 2000

Arginine 447 Plays A Pivotal Role In Substrate Interactions In A Neuronal Glutamate Transporter, Annie Bendahan, Ayelet Armon, Navid Madani, Michael Kavanaugh, Baruch I. Kanner

Biomedical and Pharmaceutical Sciences Faculty Publications

Glutamate transporters from the central nervous system play a crucial role in the clearance of the transmitter from the synaptic cleft. Glutamate is cotransported with sodium ions, and the electrogenic translocation cycle is completed by countertransport of potassium. Mutants that cannot interact with potassium are only capable of catalyzing electroneutral exchange. Here we identify a residue involved in controlling substrate recognition in the neuronal transporter EAAC-1 that transports acidic amino acids as well as cysteine. When arginine 447, a residue conserved in all glutamate transporters, is replaced by cysteine, transport of glutamate or aspartate is abolished, but sodium-dependent cysteine transport …

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Health Professions Division Catalog Academic Year 2000-2001, Nova Southeastern University Jan 2000

Health Professions Division Catalog Academic Year 2000-2001, Nova Southeastern University

Health Professions Divisions Course Catalogs and Course Descriptions

No abstract provided.

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Sistem Maklumat Perubatan Tradisional Melayu, Omar Rosfazila Jan 2000

Sistem Maklumat Perubatan Tradisional Melayu, Omar Rosfazila

Student Works (2000-2009)

Sistem Maklumat Perubatan Tradisional Melayu adalah merupakan satu sistem makumat berkomputer yang dibangunkan di halaman web. Ia bertujuan untuk membantu pengguna mencapai maklumat mengenai (ubatan tradisional serta tumbuhan berubat yang) diamalkan oleh orang Melayu. Sistem ini akan menceritakan serba sedikit tentang sejarah penggunaan perubatan tradisional. Pengguna sistem juga dijangka dapat mengemukan pertanyaan dan memberi sebarang komen yang berkaitan dengan sistem. Bantuan kepada pengguna sistem tentang cara menggunakan sistem turut dipaparkan dalam pembangunan system ini nanti. Sistem ini juga membolehkan pihak pentadbir membuat pengemaskinian maklumat mengikut kesesuaian semasa dan pembaharuan. Ia adalah sejajar dengan matlamat untuk memastikan penyimpanan maklwnat yang lebih …

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Role Of KAtp Channels In Reduced Antinociceptive Effect Of Morphine In Streptozotocin-Induced Diabetic Mice, Vivek Sood, Ajay Sharma, Manjeet Singh Jan 2000

Role Of KAtp Channels In Reduced Antinociceptive Effect Of Morphine In Streptozotocin-Induced Diabetic Mice, Vivek Sood, Ajay Sharma, Manjeet Singh

Pharmacy Faculty Articles and Research

The nociceptive effect was measured using withdrawal latency in tail flick test in mice rendered diabetic by administering streptozotocin (200 mg/kg, i.p.). The antinociceptive effect of morphine (4 and 8 mg/kg, s.c.) and cromakalim, a KATP channel opener, (0.3, 1 and 2 micrograms, i.c.v.) was significantly reduced in diabetic mice. Moreover, co-administration of cromakalim(0.3 microgram) did not alter the reduced antinociceptive effect of morphine(4 mg/kg) in diabetic mice. Spleenectomy in diabetic mice restored the decrease in antinociceptive effect of morphine and cromakalim. Multiple dose treatment with insulin to maintain euglycaemia for 3 days in diabetic mice prevented the decrease in …

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Effect Of Actinomycin D And Cycloheximide On Ischemic Preconditioning-Induced Delayed Cardioprotective Effect In Rats, Devinder Singh, Ajay Sharma, Manjeet Singh Jan 2000

Effect Of Actinomycin D And Cycloheximide On Ischemic Preconditioning-Induced Delayed Cardioprotective Effect In Rats, Devinder Singh, Ajay Sharma, Manjeet Singh

Pharmacy Faculty Articles and Research

The present study was designed to investigate the effect of actinomycin D, a transcription inhibitor, and cycloheximide, a translation inhibitor, on the delayed cardioprotective effect of ischemic preconditioning. Left thoracotomy was performed in anaesthetized rats at 4th/5th intercostal space and polypropylene suture (5-0) was employed to occlude left common coronary artery. Ischemic preconditioning was produced by four episodes of 5 min of coronary artery occlusion followed by 5 min of reperfusion and thoracic cavity was sutured. Left thoracotomy was performed again after 24 hr of ischemic preconditioning and left coronary artery was occluded for 30 min followed by reperfusion for …

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Investigations Of The Absorption And Metabolismof Antioxidant Flavonols, Abdul Aziz Azlina Jan 2000

Investigations Of The Absorption And Metabolismof Antioxidant Flavonols, Abdul Aziz Azlina

Student Works (2000-2009)

Flavonols are polyphenols, secondary plant metabolites commonly found in plants and foods of plant origin. They have widespread biological properties in the human body. The recent discovery of their potential antioxidant activities has prompted extensive research. Flavonols particularly quercetin are potent antioxidants with higher antioxidant properties than the well known antioxidant vitamins C and E. Several epidemiology studies have demonstrated a strong inverse association between flavonoid intake and risk of coronary heart disease. The association with cancer is less defined with only some studies showing an inverse association and others not. In view of their potential to act as antioxidants …

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Modulation Of The Pharmacokinetics And Pharmacodynamics Of Proteins By Polyethylene Glycol Conjugation, Reza Mehvar Jan 2000

Modulation Of The Pharmacokinetics And Pharmacodynamics Of Proteins By Polyethylene Glycol Conjugation, Reza Mehvar

Pharmacy Faculty Articles and Research

With the rapid advances in the field of biotechnology during the last decade, many peptides and proteins have been produced and evaluated for therapy of various diseases, including cancer. However, rapid clearance and the possibility of immunogenicity after the in vivo administration of these biotechnology-driven products have impeded their marketing. To circumvent these problems, synthetic and natural polymers such as polyethylene glycol (PEG) and dextrans, respectively, have been covalently attached to proteins, and some of these protein-polymer conjugates have shown promising therapeutic results. The conjugation of proteins with polymers usually causes a reduction in the recognition of the protein by …

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Protein Adducts Of Iso[4]Levuglandin E2, A Product Of The Isoprostane Pathway, In Oxidized Low Density Lipoprotein, Robert G. Salomon, Wei Sha, Cynthia Brame, Kamaljit Kaur, Ganesamoorthy Subbanagounder, June O'Neil, Henry F. Hoff, L. Jackson Roberts Ii Jul 1999

Protein Adducts Of Iso[4]Levuglandin E2, A Product Of The Isoprostane Pathway, In Oxidized Low Density Lipoprotein, Robert G. Salomon, Wei Sha, Cynthia Brame, Kamaljit Kaur, Ganesamoorthy Subbanagounder, June O'Neil, Henry F. Hoff, L. Jackson Roberts Ii

Pharmacy Faculty Articles and Research

Levuglandin (LG) E2, a cytotoxic seco prostanoic acid co-generated with prostaglandins by nonenzymatic rearrangements of the cyclooxygenase-derived endoperoxide, prostaglandin H2, avidly binds to proteins. That LGE2-protein adducts can also be generated nonenzymatically is demonstrated by their production during free radical-induced oxidation of low density lipoprotein (LDL). Like oxidized LDL, LGE2-LDL, but not native LDL, undergoes receptor-mediated uptake and impaired processing by macrophage cells. Since radical-induced lipid oxidation produces isomers of prostaglandins, isoprostanes (isoPs), via endoperoxide intermediates, we postulated previously that a similar family of LG isomers, isoLGs, is cogenerated with isoPs. Now …

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A Critical Site In The Core Of The Ccr5 Chemokine Receptor Required For Binding And Infectivity Of Human Immunodeficiency Virus Type 1, Salvatore J. Siciliano, Shawn E. Kuhmann, Youmin Weng, Navid Madani, Martin S. Springer, Janet E. Lineberger, Renee Danzeisen, Michael D. Miller, Michael Kavanaugh, Julie A. Demartino, David Kabat Jan 1999

A Critical Site In The Core Of The Ccr5 Chemokine Receptor Required For Binding And Infectivity Of Human Immunodeficiency Virus Type 1, Salvatore J. Siciliano, Shawn E. Kuhmann, Youmin Weng, Navid Madani, Martin S. Springer, Janet E. Lineberger, Renee Danzeisen, Michael D. Miller, Michael Kavanaugh, Julie A. Demartino, David Kabat

Biomedical and Pharmaceutical Sciences Faculty Publications

Like the CCR5 chemokine receptors of humans and rhesus macaques, the very homologous (∼98–99% identical) CCR5 of African green monkeys (AGMs) avidly binds β-chemokines and functions as a coreceptor for simian immunodeficiency viruses. However, AGM CCR5 is a weak coreceptor for tested macrophage-tropic (R5) isolates of human immunodeficiency virus type 1 (HIV-1). Correspondingly, gp120 envelope glycoproteins derived from R5 isolates of HIV-1 bind poorly to AGM CCR5. We focused on a unique extracellular amino acid substitution at the juncture of transmembrane helix 4 (TM4) and extracellular loop 2 (ECL2) (Arg for Gly at amino acid 163 (G163R)) as the likely …

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Health Professions Division Catalog Academic Year 1999-2000, Nova Southeastern University Jan 1999

Health Professions Division Catalog Academic Year 1999-2000, Nova Southeastern University

Health Professions Divisions Course Catalogs and Course Descriptions

No abstract provided.

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Neurotransmitter Transport: Models In Flux, Michael Kavanaugh Jan 1998

Neurotransmitter Transport: Models In Flux, Michael Kavanaugh

Biomedical and Pharmaceutical Sciences Faculty Publications

Physiologists say that ions and neutral solutes can cross biological membranes via “transporters” and “channels.” We tend to think about the difference between transporters and channels in terms of gating mechanisms. Ion channels exhibit a wide range of selectivity properties and permeation rates, but their gating at the most basic level can be thought of in terms of a single barrier or gate acting as a switch. When the gate is closed, ions can’t permeate; when the gate is opened, a permeation pathway for ions allows flux, often at very high rates (up to 108/sec). Transporters and ion …

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Excitatory Amino Acid Transporters Of The Salamander Retina: Identification, Localization, And Function, Scott Eliasof, Jeffrey L. Arriza, Barbara H. Leighton, Michael Kavanaugh, Susan G. Amara Jan 1998

Excitatory Amino Acid Transporters Of The Salamander Retina: Identification, Localization, And Function, Scott Eliasof, Jeffrey L. Arriza, Barbara H. Leighton, Michael Kavanaugh, Susan G. Amara

Biomedical and Pharmaceutical Sciences Faculty Publications

The rapid re-uptake of extracellular glutamate mediated by a family of high-affinity glutamate transporter proteins is essential to continued glutamatergic signaling and neuronal viability, but the contributions of individual transporter subtypes toward cellular physiology are poorly understood. Because the physiology of glutamate transport in the salamander retina has been well described, we have examined the expression and function of glutamate transporter subtypes in this preparation. cDNAs encoding five distinct salamander excitatory amino acid transporter (sEAAT) subtypes were isolated, and their molecular properties and distributions of expression were compared. We report evidence that at least four distinct sEAAT subtypes are expressed …

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Molecular Determinant Of Ion Selectivity Of A (Na+ + K+)-Coupled Rat Brain Glutamate Transporter, Yumin Zhang, Annie Bendahan, Ruth Zarbiv, Michael Kavanaugh, Baruch I. Kanner Jan 1998

Molecular Determinant Of Ion Selectivity Of A (Na+ + K+)-Coupled Rat Brain Glutamate Transporter, Yumin Zhang, Annie Bendahan, Ruth Zarbiv, Michael Kavanaugh, Baruch I. Kanner

Biomedical and Pharmaceutical Sciences Faculty Publications

Glutamate transporters remove this neurotransmitter from the synaptic cleft by a two-stage electrogenic process, in which glutamate is first cotransported with three sodium ions and a proton. Subsequently, the cycle is completed by translocation of a potassium ion in the opposite direction. Recently, we have identified an amino acid residue of the glutamate transporter GLT-1 (Glu-404) that influences potassium coupling. We have now analyzed the effect of seven other amino acid residues in the highly conserved region surrounding this site. One of these residues, Tyr-403, also proved important for potassium coupling, because mutation to Phe (Y403F) resulted in an electroneutral …

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Cysteine Scanning Of The Surroundings Of An Alkali-Ion Binding Site Of The Glutamate Transporter Glt-1 Reveals A Conformationally Sensitive Residue, Ruth Zarbiv, Myriam Grunewald, Michael Kavanaugh, Baruch I. Kanner Jan 1998

Cysteine Scanning Of The Surroundings Of An Alkali-Ion Binding Site Of The Glutamate Transporter Glt-1 Reveals A Conformationally Sensitive Residue, Ruth Zarbiv, Myriam Grunewald, Michael Kavanaugh, Baruch I. Kanner

Biomedical and Pharmaceutical Sciences Faculty Publications

Glutamate transporters remove this transmitter from the extracellular space by cotransport with three sodium ions and a proton. The cycle is completed by translocation of a potassium ion in the opposite direction. Recently we have identified two adjacent amino acid residues of the glutamate transporter GLT-1 that influence potassium coupling. Using the scanning cysteine accessibility method we have now explored the highly conserved region surrounding them. Replacement of each of the five consecutive residues 396–400 by cysteine abolished transport activity but at several other positions the substitution is tolerated. One residue, tyrosine 403, was identified where cysteine substitution renders the …

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Gp120 Envelope Glycoproteins Of Human Immunodeficiency Viruses Competitively Antagonize Signaling By Coreceptors Cxcr4 And Ccr5, Navid Madani, Susan L. Kozak, Michael Kavanaugh, David Kabat Jan 1998

Gp120 Envelope Glycoproteins Of Human Immunodeficiency Viruses Competitively Antagonize Signaling By Coreceptors Cxcr4 And Ccr5, Navid Madani, Susan L. Kozak, Michael Kavanaugh, David Kabat

Biomedical and Pharmaceutical Sciences Faculty Publications

Signal transductions by the dual-function CXCR4 and CCR5 chemokine receptors/HIV type 1 (HIV-1) coreceptors were electrophysiologically monitored in Xenopus laevis oocytes that also coexpressed the viral receptor CD4 and a G protein-coupled inward-rectifying K+ channel (Kir 3.1). Large Kir 3.1-dependent currents generated in response to the corresponding chemokines (SDF-1α for CXCR4 and MIP-1α; MIP-1β and RANTES for CCR5) were blocked by pertussis toxin, suggesting involvement of inhibitory guanine nucleotide-binding proteins. Prolonged exposures to chemokines caused substantial but incomplete desensitization of responses with time constants of 5–7 min and recovery time constants of 12–19 min. CXCR4 and CCR5 exhibited heterologous …

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Arachidonic Acid Activates A Proton Current In The Rat Glutamate Transporter Eaat4, Anastassios V. Tzingounis, Chien-Liang Lin, Jeffrey D. Rothstein, Michael Kavanaugh Jan 1998

Arachidonic Acid Activates A Proton Current In The Rat Glutamate Transporter Eaat4, Anastassios V. Tzingounis, Chien-Liang Lin, Jeffrey D. Rothstein, Michael Kavanaugh

Biomedical and Pharmaceutical Sciences Faculty Publications

The excitatory amino acid transporter EAAT4 is expressed predominantly in Purkinje neurons in the rat cerebellum (1-3), and it participates in postsynaptic reuptake of glutamate released at the climbing fiber synapse (4). Transporter-mediated currents in Purkinje neurons are increased more than 3-fold by arachidonic acid, a second messenger that is liberated following depolarization-induced Ca2+ activation of phospholipase A2 (5). In this study we demonstrate that application of arachidonic acid to oocytes expressing rat EAAT4 increased glutamate-induced currents to a similar extent. However, arachidonic acid did not cause an increase in the rate …

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Macroscopic And Microscopic Properties Of A Cloned Glutamate Transporter/Chloride Channel, Jacques I. Wadiche, Michael Kavanaugh Jan 1998

Macroscopic And Microscopic Properties Of A Cloned Glutamate Transporter/Chloride Channel, Jacques I. Wadiche, Michael Kavanaugh

Biomedical and Pharmaceutical Sciences Faculty Publications

The behavior of a Cl− channel associated with a glutamate transporter was studied using intracellular and patch recording techniques in Xenopus oocytes injected with human EAAT1 cRNA. Channels could be activated by application of glutamate to either face of excised membrane patches. The channel exhibited strong selectivity for amphipathic anions and had a minimum pore diameter of ∼5Å. Glutamate flux exhibited a much greater temperature dependence than Cl− flux. Stationary and nonstationary noise analysis was consistent with a sub-femtosiemen Cl− conductance and a maximum channelPo ≪ 1. The glutamate binding rate was similar to estimates …

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Health Professions Division Catalog Academic Year 1998-1999, Nova Southeastern University Jan 1998

Health Professions Division Catalog Academic Year 1998-1999, Nova Southeastern University

Health Professions Divisions Course Catalogs and Course Descriptions

No abstract provided.

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Multiple Ionic Conductances Of The Human Dopamine Transporter: The Actions Of Dopamine And Psychostimulants, Mark S. Sonders, Si-Jia Zhu, Nancy R. Zahniser, Michael Kavanaugh, Susan G. Amara Jan 1997

Multiple Ionic Conductances Of The Human Dopamine Transporter: The Actions Of Dopamine And Psychostimulants, Mark S. Sonders, Si-Jia Zhu, Nancy R. Zahniser, Michael Kavanaugh, Susan G. Amara

Biomedical and Pharmaceutical Sciences Faculty Publications

Electrophysiological and pharmacological studies of a cloned human dopamine transporter (hDAT) were undertaken to investigate the mechanisms of transporter function and the actions of drugs at this target. Using two-electrode voltage-clamp techniques with hDAT-expressing Xenopus laevis oocytes, we show that hDAT can be considered electrogenic by two criteria. (1) Uptake of hDAT substrates gives rise to a pharmacologically appropriate “transport-associated” current. (2) The velocity of DA uptake measured in oocytes clamped at various membrane potentials was voltage-dependent, increasing with hyperpolarization. Concurrent measurement of transport-associated current and substrate flux in individual oocytes revealed that charge movement during substrate translocation was greater …

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Excitatory Amino Acid Transporter 5, A Retinal Glutamate Transporter Coupled To A Chloride Conductance, Jeffrey L. Arriza, Scott Eliasof, Michael Kavanaugh, Susan G. Amara Jan 1997

Excitatory Amino Acid Transporter 5, A Retinal Glutamate Transporter Coupled To A Chloride Conductance, Jeffrey L. Arriza, Scott Eliasof, Michael Kavanaugh, Susan G. Amara

Biomedical and Pharmaceutical Sciences Faculty Publications

Although a glutamate-gated chloride conductance with the properties of a sodium-dependent glutamate transporter has been described in vertebrate retinal photoreceptors and bipolar cells, the molecular species underlying this conductance has not yet been identified. We now report the cloning and functional characterization of a human excitatory amino acid transporter, EAAT5, expressed primarily in retina. Although EAAT5 shares the structural homologies of the EAAT gene family, one novel feature of the EAAT5 sequence is a carboxy-terminal motif identified previously in N-methyl-d-aspartate receptors and potassium channels and shown to confer interactions with a family of synaptic proteins that promote ion channel …

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Aspartate 19 And Glutamate 121 Are Critical For Transport Function Of The Myo-Inositol/H+ Symporter From Leishmania Donovani, Andreas Seyfang, Michael Kavanaugh, Scott M. Landfear Jan 1997

Aspartate 19 And Glutamate 121 Are Critical For Transport Function Of The Myo-Inositol/H+ Symporter From Leishmania Donovani, Andreas Seyfang, Michael Kavanaugh, Scott M. Landfear

Biomedical and Pharmaceutical Sciences Faculty Publications

The protozoan flagellate Leishmania donovani has an active myo-inositol/proton symporter (MIT), which is driven by a proton gradient across the parasite membrane. We have used site-directed mutagenesis in combination with functional expression of transporter mutants in Xenopusoocytes and overexpression in Leishmania transfectants to investigate the significance of acidic transmembrane residues for proton relay and inositol transport. MIT has only three charged amino acids within predicted transmembrane domains. Two of these residues, Asp19 (TM1) and Glu121 (TM4), appeared to be critical for transport function of MIT, with a reduction of inositol transport to about 2% of wild-type …

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Tyrosine 140 Of The Γ-Aminobutyric Acid Transporter Gat-1 Plays A Critical Role In Neurotransmitter Recognition, Yona Bismuth, Michael Kavanaugh, Baruch I. Kanner Jan 1997

Tyrosine 140 Of The Γ-Aminobutyric Acid Transporter Gat-1 Plays A Critical Role In Neurotransmitter Recognition, Yona Bismuth, Michael Kavanaugh, Baruch I. Kanner

Biomedical and Pharmaceutical Sciences Faculty Publications

The γ-aminobutyric acid (GABA) transporter GAT-1 is located in nerve terminals and catalyzes the electrogenic reuptake of the neurotransmitter with two sodium ions and one chloride. We now identify a single tyrosine residue that is critical for GABA recognition and transport. It is completely conserved throughout the superfamily, and even substitution to the other aromatic amino acids, phenylalanine (Y140F) and tryptophan (Y140W), results in completely inactive transporters. Electrophysiological characterization reveals that both mutant transporters exhibit the sodium-dependent transient currents associated with sodium binding as well as the chloride-dependent lithium leak currents characteristic of GAT-1. On the other hand, in both …

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Mutation Of An Amino Acid Residue Influencing Potassium Coupling In The Glutamate Transporter Glt-1 Induces Obligate Exchange, Michael Kavanaugh, Annie Bendahan, Noa Zerangue, Yumin Zhang, Baruch I. Kanner Jan 1997

Mutation Of An Amino Acid Residue Influencing Potassium Coupling In The Glutamate Transporter Glt-1 Induces Obligate Exchange, Michael Kavanaugh, Annie Bendahan, Noa Zerangue, Yumin Zhang, Baruch I. Kanner

Biomedical and Pharmaceutical Sciences Faculty Publications

Glutamate transporters maintain low synaptic concentrations of neurotransmitter by coupling uptake to flux of other ions. After cotransport of glutamic acid with Na+, the cycle is completed by countertransport of K+. We have identified an amino acid residue (glutamate 404) influencing ion coupling in a domain of the transporter implicated previously in kainate binding. Mutation of this residue to aspartate (E404D) prevents both forward and reverse transport induced by K+. Sodium-dependent transmitter exchange and a transporter-mediated chloride conductance are unaffected by the mutation, indicating that this residue selectively influences potassium flux coupling. The results …

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Anion Induced Blue To Purple Transition In Bacteriorhodopsin, Mrunalini Pattarkine, Anil K. Singh Jun 1996

Anion Induced Blue To Purple Transition In Bacteriorhodopsin, Mrunalini Pattarkine, Anil K. Singh

Faculty Works

Purple membrane (PM, λ" role="presentation">λmax" role="presentation">max 570 nm) of H. halobium on treatment with sulphuric acid changes its colour to blue (λ" role="presentation">λmax" role="presentation">max 608 nm). The purple chromophore can be regenerated from the blue chromophore by exogeneous addition of anions such as CI−" role="presentation">− and HPO42−" role="presentation">2−4. Chloride ion is found to be more effective than the dibasic phosphate ion in regenerating the purple chromophore. Nevertheless, one thing common to the anion regeneration is that both CI−" role="presentation">− and HPO42−" role="presentation">2−4 show marked pH effect. At pH 1.0 the efficiency of …

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Asct-1 Is A Neutral Amino Acid Exchanger With Chloride Channel Activity, Noa Zerangue, Michael Kavanaugh Jan 1996

Asct-1 Is A Neutral Amino Acid Exchanger With Chloride Channel Activity, Noa Zerangue, Michael Kavanaugh

Biomedical and Pharmaceutical Sciences Faculty Publications

The ubiquitous transport activity known as system ASC is characterized by a preference for small neutral amino acids including alanine, serine, and cysteine. ASCT-1 and ASCT-2, recently cloned transporters exhibiting system ASC-like selectivity, are members of a major amino acid transporter family that includes a number of glutamate transporters. Here we show that ASCT1 functions as an electroneutral exchanger that mediates negligible net amino acid flux. The electrical currents previously shown to be associated with ASCT1-mediated transport result from activation of a thermodynamically uncoupled chloride conductance with permeation properties similar to those described for the glutamate transporter subfamily. Like glutamate …

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Kinetics And Stoichiometry Of A Proton/Myo-Inositol Cotransporter, Elizabeth M. Klamo, Mark E. Drew, Scott M. Landfear, Michael Kavanaugh Jan 1996

Kinetics And Stoichiometry Of A Proton/Myo-Inositol Cotransporter, Elizabeth M. Klamo, Mark E. Drew, Scott M. Landfear, Michael Kavanaugh

Biomedical and Pharmaceutical Sciences Faculty Publications

Voltage clamp recording was used to measure steady-state and presteady-state currents mediated by a myo-inositol transporter cloned from Leishmania donovani and expressed in Xenopus oocytes. Application of myo-inositol resulted in inward currents, which did not require external sodium and which were increased by increasing the extracellular proton concentration and by membrane hyperpolarization. Alkalinization of the extracellular space occurred concomitantly with myo-inositol influx. Correlation of membrane currents with radiolabeled myo-inositol flux revealed that one positive charge is translocated with each molecule of myo-inositol, consistent with cotransport of one proton. The transport concentration dependence on both species …

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Health Professions Division Academic Year 1996-1997, Nova Southeastern University Jan 1996

Health Professions Division Academic Year 1996-1997, Nova Southeastern University

Health Professions Divisions Course Catalogs and Course Descriptions

No abstract provided.

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Differential Modulation Of Human Glutamate Transporter Subtypes By Arachidonic Acid, Noa Zerangue, Jeffrey L. Arriza, Susan G. Amara, Michael Kavanaugh Jan 1995

Differential Modulation Of Human Glutamate Transporter Subtypes By Arachidonic Acid, Noa Zerangue, Jeffrey L. Arriza, Susan G. Amara, Michael Kavanaugh

Biomedical and Pharmaceutical Sciences Faculty Publications

Arachidonic acid has been proposed to be a messenger molecule released following synaptic activation of glutamate receptors and during ischemia. Here we demonstrate that micromolar levels of arachidonic acid inhibit glutamate uptake mediated by EAAT1, a human excitatory amino acid transporter widely expressed in brain and cerebellum, by reducing the maximal transport rate approximately 30%. In contrast, arachidonic acid increased transport mediated by EAAT2, a subtype abundantly expressed in forebrain and midbrain, by causing the apparent affinity for glutamate to increase more than 2-fold. The results demonstrate that the response of different glutamate transporter subtypes to arachidonic acid could influence …

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