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Articles 91 - 109 of 109

Full-Text Articles in Medical Biochemistry

Characterization Of The Formate (For) Locus, Which Encodes The Cytosolic Serine Hydroxymethyltransferase Of Neurospora Crassa., C. Robertson Mcclung, Cynthia R. Davis, Karen M. Page, Sylvia A. Denome Apr 1992

Characterization Of The Formate (For) Locus, Which Encodes The Cytosolic Serine Hydroxymethyltransferase Of Neurospora Crassa., C. Robertson Mcclung, Cynthia R. Davis, Karen M. Page, Sylvia A. Denome

Dartmouth Scholarship

Serine hydroxymethyltransferase (SHMT) occupies a central position in one-carbon (C1) metabolism, catalyzing the reaction of serine and tetrahydrofolate to yield glycine and 5,10-methylenetetrahydrofolate. Methylenetetrahydrofolate serves as a donor of C1 units for the synthesis of numerous compounds, including purines, thymidylate, lipids, and methionine. We provide evidence that the formate (for) locus of Neurospora crassa encodes cytosolic SHMT. The for+ gene was localized to a 2.8-kb BglII fragment by complementation (restoration to formate-independent growth) of a strain carrying a recessive for allele, which confers a growth requirement for formate. The for+ gene encodes a polypeptide of 479 amino acids which shows …

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The Ability Of Simian Virus 40 Large T Antigen To Immortalize Primary Mouse Embryo Fibroblasts Cosegregates With Its Ability To Bind To P53., Jiyue Y. Zhu, Marina Abate, Philip W. Rice, Charles N. Cole Dec 1991

The Ability Of Simian Virus 40 Large T Antigen To Immortalize Primary Mouse Embryo Fibroblasts Cosegregates With Its Ability To Bind To P53., Jiyue Y. Zhu, Marina Abate, Philip W. Rice, Charles N. Cole

Dartmouth Scholarship

The large T antigen encoded by simian virus 40 (SV40) plays essential roles in the infection of permissive cells, leading to production of progeny virions, and in the infection of nonpermissive cells, leading to malignant transformation. Primary mouse embryo fibroblasts (MEFs) are nonpermissive for SV40, and infection by wild-type SV40 leads to immortalization and transformation of a small percentage of infected cells. We examined the ability of an extensive set of mutants whose lesions affect SV40 large T antigen to immortalize MEFs. We found that immortalization activity was retained by all mutants whose lesions are located upstream of codon 346. …

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Translocation Of The Glucose Transporter Glut4 In Cardiac Myocytes Of The Rat., Jan W. Slot, Hans J. Geuze, Sander Gigengack, David E. James, Gustav E. Lienhard Sep 1991

Translocation Of The Glucose Transporter Glut4 In Cardiac Myocytes Of The Rat., Jan W. Slot, Hans J. Geuze, Sander Gigengack, David E. James, Gustav E. Lienhard

Dartmouth Scholarship

The insulin-regulated glucose transporter GLUT4 was immunolocalized in rat cardiac muscle under conditions of basal and stimulated glucose uptake, achieved by fasting and a combined exercise/insulin stimulus, respectively. In basal myocytes there was very little (less than 1%) GLUT4 in the different domains of the plasma membrane (sarcolemma, intercalated disk, and transverse tubular system). GLUT4 was localized in small tubulo-vesicular elements that occur predominantly near the sarcolemma and the transverse tubular system and in the trans-Golgi region. Upon stimulation approximately 42% of GLUT4 was found in the plasma membrane. Each domain of the plasma membrane contributed equally to this effect. …

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Mapping The Transcriptional Transactivation Function Of Simian Virus 40 Large T Antigen., Jiyue Y. Zhu, Philip W. Rice, Michele Chamberlain, Charles N. Cole Jun 1991

Mapping The Transcriptional Transactivation Function Of Simian Virus 40 Large T Antigen., Jiyue Y. Zhu, Philip W. Rice, Michele Chamberlain, Charles N. Cole

Dartmouth Scholarship

T antigen is able to transactivate gene expression from the simian virus 40 (SV40) late promoter and from several other viral and cellular promoters. Neither the mechanisms of transactivation by T antigen nor the regions of T antigen required for this activity have been determined. To address the latter point, we have measured the ability of a set of SV40 large T antigen mutants to stimulate gene expression in CV-1 monkey kidney cells from the SV40 late promoter and Rous sarcoma virus (RSV) long terminal repeat (LTR) promoter. Transactivation, although reduced, was retained by an N-terminal 138-amino-acid fragment of T …

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Neurospora Crassa Clock-Controlled Genes Are Regulated At The Level Of Transcription., Jennifer J. Loros, Jay C. Dunlap Jan 1991

Neurospora Crassa Clock-Controlled Genes Are Regulated At The Level Of Transcription., Jennifer J. Loros, Jay C. Dunlap

Dartmouth Scholarship

Although an extensive number of biological processes are under the daily control of the circadian biological clock, little is known about how the clock maintains its regulatory networks within a cell. An important aspect of this temporal control is the daily control of gene expression. Previously we identified two morning-specific genes that are regulated by the clock through daily control of gene expression (J. Loros, S. Denome, and J.C. Dunlap, Science 243:385-388, 1989). We have now introduced a method for transcriptional analysis in Neurospora crassa and used this nuclear run-on procedure to show that regulation of mRNA abundance for these …

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The Growth Of Simian Virus 40 (Sv40) Host Range/Adenovirus Helper Function Mutants In An African Green Monkey Cell Line That Constitutively Expresses The Sv40 Agnoprotein., Terryl P. Stacy, Michele Chamberlain, Susan Carswell, Charles N. Cole Jul 1990

The Growth Of Simian Virus 40 (Sv40) Host Range/Adenovirus Helper Function Mutants In An African Green Monkey Cell Line That Constitutively Expresses The Sv40 Agnoprotein., Terryl P. Stacy, Michele Chamberlain, Susan Carswell, Charles N. Cole

Dartmouth Scholarship

The simian virus 40 T-antigen carboxy-terminal mutants, dlA2459 and dlA2475, are cell line and temperature dependent for growth and plaque formation in monkey kidney cells. Although these mutants did form plaques on BSC-1 cells at 37 degrees C, they were about fivefold less efficient for plaque formation than wild-type simian virus 40. These mutants did not grow in CV-1 cells and did not synthesize agnoprotein in those cells. CV-1 cells which constitutively express the agnoprotein were permissive for mutant plaque formation. However, late mRNAs, virion proteins, and progeny virion yields did not accumulate to wild-type levels during mutant infection of …

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Fibril In Senile Systemic Amyloidosis Is Derived From Normal Transthyretin., Per Westermark, Knut Sletten, Bjorn Johansson, Gibbons G. Cornwell Apr 1990

Fibril In Senile Systemic Amyloidosis Is Derived From Normal Transthyretin., Per Westermark, Knut Sletten, Bjorn Johansson, Gibbons G. Cornwell

Dartmouth Scholarship

The amyloid fibril in senile systemic amyloidosis (SSA), like that of familial amyloidotic polyneuropathy, is derived from transthyretin (TTR). SSA, however, is a common disease, affecting to some degree 25% of the population greater than 80 years old. In familial amyloidotic polyneuropathy, the amyloidogenesis has been considered to depend on point mutations leading to TTR variants. We show that the TTR molecule in SSA, on the other hand, has a normal primary structure. Factors other than the primary structure of TTR must therefore be important in the pathogenesis of TTR-derived amyloid.

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Simian Virus 40 Host Range/Helper Function Mutations Cause Multiple Defects In Viral Late Gene Expression., Terryl Stacy, Michele Chamberlain, Charles N. Cole Dec 1989

Simian Virus 40 Host Range/Helper Function Mutations Cause Multiple Defects In Viral Late Gene Expression., Terryl Stacy, Michele Chamberlain, Charles N. Cole

Dartmouth Scholarship

Simian virus 40 (SV40) deletion mutants dlA2459 and dlA2475 express T antigens that lack the normal carboxy terminus. These mutants are called host range/helper function (hr/hf) mutants because they form plaques at 37 degrees C on BSC-1 and Vero monkey kidney cell lines but not on CV-1p monkey kidney cells. Wild-type SV40 can provide a helper function to permit growth of human adenoviruses in monkey kidney cells; the hr/hf mutants cannot. Progeny yields of hr/hf mutants are also cold sensitive in all cell lines tested. Patterns of viral macromolecular synthesis in three cell lines (Vero, BSC-1, and CV-1) at three …

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Linker Insertion Mutants Of Simian Virus 40 Large T Antigen That Show Trans-Dominant Interference With Wild-Type Large T Antigen Map To Multiple Sites Within The T-Antigen Gene., Jiyue Y. Zhu, Charles N. Cole Nov 1989

Linker Insertion Mutants Of Simian Virus 40 Large T Antigen That Show Trans-Dominant Interference With Wild-Type Large T Antigen Map To Multiple Sites Within The T-Antigen Gene., Jiyue Y. Zhu, Charles N. Cole

Dartmouth Scholarship

Linker insertion mutants affecting the simian virus 40 (SV40) large tumor (T) antigen were constructed by inserting a 12-base-pair oligonucleotide linker into restriction endonuclease cleavage sites located within the early region of SV40. One mutant, with the insertion at amino acid 5, was viable in CV-1p and BSC-1 cells, indicating that sequences very close to the amino terminus of large T could be altered without affecting the lytic infection cycle of SV40. All other mutants affecting large T were not viable. In complementation assays between the linker insertion mutants and either a late-gene mutant, dlBC865, or a host range/helper function …

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Patterns Of Polyadenylation Site Selection In Gene Constructs Containing Multiple Polyadenylation Signals., Roger Denome, Charles Cole Nov 1988

Patterns Of Polyadenylation Site Selection In Gene Constructs Containing Multiple Polyadenylation Signals., Roger Denome, Charles Cole

Dartmouth Scholarship

We have constructed a series of plasmids containing multiple polyadenylation signals downstream of the herpes simplex virus type 1 (HSV) thymidine kinase (tk)-coding region. The signals used were from the simian virus 40 (SV40) late gene, the HSV tk gene, and an AATAAA-containing segment of the SV40 early region. This last fragment signals polyadenylation poorly in our constructs and not at all during SV40 infection. All plasmids contained the SV40 origin of replication. Plasmids were transfected into Cos-1 cells; after 48 h, cytoplasmic RNA was isolated and the quantity and 3'-end structure of tk mRNAs was analyzed by using S1 …

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Insulin Stimulates The Dephosphorylation And Activation Of Acetyl-Coa Carboxylase., Lee A. Witters, Thomas D. Watts, Diana L. Daniels, Joseph L. Evans Aug 1988

Insulin Stimulates The Dephosphorylation And Activation Of Acetyl-Coa Carboxylase., Lee A. Witters, Thomas D. Watts, Diana L. Daniels, Joseph L. Evans

Dartmouth Scholarship

The mechanism underlying the ability of insulin to acutely activate acetyl-CoA carboxylase [acetyl-CoA: carbon-dioxide ligase (ADP-forming), EC 6.4.1.2; AcCoA-Case] has been examined in Fao Reuber hepatoma cells. Insulin promotes the rapid activation of AcCoACase, as measured in cell lysates, and this stimulation persists to the same degree after isolation of AcCoACase by avidin-Sepharose chromatography. The insulin-stimulated enzyme, as compared with control enzyme, exhibits an increase in both citrate-independent and -dependent activity and a decrease in the Ka for citrate. Direct examination of the phosphorylation state of isolated 32P-labeled AcCoACase after insulin exposure reveals a marked decrease in total enzyme phosphorylation …

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Molecular Cloning And Sequence Analysis Of The Plasmodium Falciparum Dihydrofolate Reductase-Thymidylate Synthase Gene., David J. Bzik, Wu-Bo Li, Toshihiro Horii, Joseph Inselburg Dec 1987

Molecular Cloning And Sequence Analysis Of The Plasmodium Falciparum Dihydrofolate Reductase-Thymidylate Synthase Gene., David J. Bzik, Wu-Bo Li, Toshihiro Horii, Joseph Inselburg

Dartmouth Scholarship

Genomic DNA clones that coded for the bifunctional dihydrofolate reductase (DHFR) and thymidylate synthase (TS) (DHFR-TS) activities from a pyrimethamine-sensitive strain of Plasmodium falciparum were isolated and sequenced. The deduced DHFR-TS protein contained 608 amino acids (71,682 Da). The coding region for DHFR-TS contained no intervening sequences and had a high A + T content (75%). The DHFR domain, in the amino-terminal portion of the protein, was joined by a 94-amino acid junction sequence to the TS domain in the carboxyl-terminal portion of the protein. The TS domain was more conserved than the DHFR domain and both P. falciparum domains …

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Identification Of A Complex Associated With Processing And Polyadenylation In Vitro Of Herpes Simplex Virus Type 1 Thymidine Kinase Precursor Rna., Fang Zhang, Charles N. Cole Sep 1987

Identification Of A Complex Associated With Processing And Polyadenylation In Vitro Of Herpes Simplex Virus Type 1 Thymidine Kinase Precursor Rna., Fang Zhang, Charles N. Cole

Dartmouth Scholarship

Cleavage and polyadenylation of substrate RNAs containing the herpes simplex virus type 1 (HSV-1) thymidine kinase (tk) gene polyadenylation signal region were examined in HeLa cell nuclear extract. 3'-End RNA processing was accurate and efficient and required ATP and Mg2+. Cleavage, but not polyadenylation, occurred in the presence of EDTA or when ATP was replaced with 3' dATP (cordycepin) or AMP(CH2)PP, a nonhydrolyzable analog of ATP. Processing in vitro and in vivo showed the same signal element requirements: a series of substrates containing linker scanning, internal deletion, and small insertion mutations was processed with the same relative efficiencies and at …

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Fine-Structure Analysis Of The Processing And Polyadenylation Region Of The Herpes Simplex Virus Type 1 Thymidine Kinase Gene By Using Linker Scanning, Internal Deletion, And Insertion Mutations., Fang Zhang, Roger M. Denome, Charles N. Cole Dec 1986

Fine-Structure Analysis Of The Processing And Polyadenylation Region Of The Herpes Simplex Virus Type 1 Thymidine Kinase Gene By Using Linker Scanning, Internal Deletion, And Insertion Mutations., Fang Zhang, Roger M. Denome, Charles N. Cole

Dartmouth Scholarship

Most eucaryotic mRNAs are polyadenylated. In higher eucaryotes, the sequence AATAAA is located 7 to 30 base pairs (bp) upstream from the site of processing and polyadenylation and is a critical part of the signal for processing and polyadenylation. Efficient cleavage and polyadenylation also require sequences downstream of polyadenylation sites. The herpes simplex virus type 1 thymidine kinase (tk) gene contains two copies of the AATAAA hexanucleotide and a GT box (18 of 19 consecutive residues are G or T) previously shown to be required for efficient processing and polyadenylation of tk mRNA (C. N. Cole and T. P. Stacy, …

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Absence Of A Structural Basis For Intracellular Recognition And Differential Localization Of Nuclear And Plasma Membrane-Associated Forms Of Simian Virus 40 Large Tumor Antigen., Donald L. Jarvis, Charles N. Cole, Janet S. Butel Mar 1986

Absence Of A Structural Basis For Intracellular Recognition And Differential Localization Of Nuclear And Plasma Membrane-Associated Forms Of Simian Virus 40 Large Tumor Antigen., Donald L. Jarvis, Charles N. Cole, Janet S. Butel

Dartmouth Scholarship

The simian virus 40 large tumor antigen (T-ag) is found in both the nuclei (nT-ag) and plasma membranes (mT-ag) of simian virus 40-infected or -transformed cells. It is not known how newly synthesized T-ag molecules are recognized, sorted, and transported to their ultimate subcellular destinations. One possibility is that these events depend upon structural differences between nT-ag and mT-ag. To test this possibility, we compared the structures of nT-ag and mT-ag from simian virus 40-infected cells. No differences between the two forms of T-ag were detected by migration in polyacrylamide gels, by Staphylococcus aureus V8 partial proteolytic mapping of methionine- …

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Identification Of Sequences In The Herpes Simplex Virus Thymidine Kinase Gene Required For Efficient Processing And Polyadenylation., Charles N. Cole, Terryl P. Stacy Aug 1985

Identification Of Sequences In The Herpes Simplex Virus Thymidine Kinase Gene Required For Efficient Processing And Polyadenylation., Charles N. Cole, Terryl P. Stacy

Dartmouth Scholarship

The herpes simplex virus (HSV) type 1 thymidine kinase gene (tk) was resected from its 3' end with BAL 31 exonuclease. Two sets of plasmids were isolated that lacked information distal to the two copies of the hexanucleotide 5'-AATAAA-3' located at the 3' end of the HSV tk gene. The presence of a simian virus 40 origin of DNA replication in each plasmid facilitated analysis of patterns of transcription in transfected Cos-1 monkey cells. Transcription analyses were performed with an S1 nuclease protection assay. Efficient processing and polyadenylation at the normal site still occurred when all sequences more than 44 …

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Two Separable Functional Domains Of Simian Virus 40 Large T Antigen: Carboxyl-Terminal Region Of Simian Virus 40 Large T Antigen Is Required For Efficient Capsid Protein Synthesis., Joanne Tornow, Maryellen Polvino-Bodnar, George Santangelo, Charles N. Cole Feb 1985

Two Separable Functional Domains Of Simian Virus 40 Large T Antigen: Carboxyl-Terminal Region Of Simian Virus 40 Large T Antigen Is Required For Efficient Capsid Protein Synthesis., Joanne Tornow, Maryellen Polvino-Bodnar, George Santangelo, Charles N. Cole

Dartmouth Scholarship

The carboxyl-terminal portion of simian virus 40 large T antigen is essential for productive infection of CV-1 and CV-1p green monkey kidney cells. Mutant dlA2459, lacking 14 base pairs at 0.193 map units, was positive for viral DNA replication, but unable to form plaques in CV-1p cells (J. Tornow and C.N. Cole, J. Virol. 47:487-494, 1983). In this report, the defect of dlA2459 is further defined. Simian virus 40 late mRNAs were transcribed, polyadenylated, spliced, and transported in dlA2459-infected cells, but the level of capsid proteins produced in infected CV-1 green monkey kidney cells was extremely low. dlA2459 large T …

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Proteins Antigenically Related To The Human Erythrocyte Glucose Transporter In Normal And Rous Sarcoma Virus-Transformed Chicken Embryo Fibroblasts., Donald W. Salter, Stephen A. Baldwin, Gustav E. Lienhard, Michael J. Weber Mar 1982

Proteins Antigenically Related To The Human Erythrocyte Glucose Transporter In Normal And Rous Sarcoma Virus-Transformed Chicken Embryo Fibroblasts., Donald W. Salter, Stephen A. Baldwin, Gustav E. Lienhard, Michael J. Weber

Dartmouth Scholarship

Antibody raised against the purified human erythrocyte glucose transporter specifically precipitated four proteins from normal and Rous sarcoma virus-transformed chicken embryo cells: a major protein of Mr 41,000 and minor proteins of Mr 68,000, 73,000, and 82,000. The Mr 41,000 and 82,000 proteins were found only in a membrane fraction, not in the soluble fraction, and displayed a heterogeneous mobility on NaDodSO4/polyacrylamide gel electrophoresis, suggesting glycosylation. The Mr 41,000 and 82,000 proteins were increased in amount after malignant transformation in direct proportion to the increase in hexose transport rate, and the increase was dependent on the expression of the src …

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Isolation Of Plasma Membrane From Human Neutrophils And Determination Of Cytochrome B And Quinone Content, Edward P. Sloan, Dana R. Crawford, Donald L. Schneider May 1981

Isolation Of Plasma Membrane From Human Neutrophils And Determination Of Cytochrome B And Quinone Content, Edward P. Sloan, Dana R. Crawford, Donald L. Schneider

Dartmouth Scholarship

Analyses of plasma membrane and other subcellular fractions indicate that the primary location of cytochrome b in human neutrophils is not the plasma membrane. The procedure developed for the purification of plasma membrane from fresh human neutrophils yielded a 14-fold enrichment in the marker enzyme 5'-nucleotidase and a 10-fold enrichment in ouabain-sensitive ATPase. On sucrose density gradients, the peak density of 5'-nucleotidase activity was 1.12 g/ml, and was shifted after digitonin addition to 1.15 g/ml. Protein in the plasma membrane equalled approximately 8 percent of the whole cell protein. A b-type cytochrome was found to be present in the plasma …

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