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Articles 1 - 4 of 4
Full-Text Articles in Life Sciences
Ion Transport Processes Of Crustacean Epithelial Cells, Gregory A. Ahearn, Jeff Duerr, Zhenpeng Zhuang, Richard J. Brown, Amy Aslamkhan, Deirdre A. Killebrew
Ion Transport Processes Of Crustacean Epithelial Cells, Gregory A. Ahearn, Jeff Duerr, Zhenpeng Zhuang, Richard J. Brown, Amy Aslamkhan, Deirdre A. Killebrew
Faculty Publications - Department of Biological & Molecular Science
Epithelial cells of the gut, antennal glands, integument, and gills of crustaceans regulate the movements of ions into and across these structures and thereby influence the concentrations of ions in the hemolymph. Specific transport proteins serving cations and anions are found on apical and basolateral cell membranes of epithelia in these tissues. In recent years, a considerable research effort has been directed at elucidating their physiological and molecular properties and relating these characteristics to the overall biology of the organisms. Efforts to describe ion transport in crustaceans have focused on the membrane transfer properties of Na1/H1 exchange, calcium uptake as …
Characterization Of A Basolateral Electroneutral Na+/H+ Antiporter In Atlantic Lobster (Homarus Americanus) Hepatopancreatic Epithelial Vesicles, Jeff Duerr, Gregory A. Ahearn
Characterization Of A Basolateral Electroneutral Na+/H+ Antiporter In Atlantic Lobster (Homarus Americanus) Hepatopancreatic Epithelial Vesicles, Jeff Duerr, Gregory A. Ahearn
Faculty Publications - Department of Biological & Molecular Science
Purified basolateral membrane vesicles (BLMVs) were prepared from Atlantic lobster (Homarus americanus) hepatopancreas using a Percoll density gradient technique. Enrichments of the Na+/K+-ATPase and alkaline phosphatase activities of these vesicles were 15.4- and 1.2- fold, respectively. The presence of amiloride-sensitive Na+/H+ exchange was demonstrated. Contrary to electrogenic 2Na+/1H+ exchange on apical membranes from the same tissue, kinetic studies of Na+ transport by these basolateral membranes indicate an electroneutral antiport with a Km of 28±1.7 mmol l21 and a Jmax of 1.74±0.13 mmol mg21 min21. Amiloride interacted at a single binding site (Ki=39mmol l21) and external Li+ was shown to be …
Ca2+ And Zn2+ Are Transported By The Electrogenic 2na+/1h+ Antiporter In Echinoderm Gastrointestinal Epithelium, Zhenpeng Zhuang, Jeff Duerr, Gregory A. Ahearn
Ca2+ And Zn2+ Are Transported By The Electrogenic 2na+/1h+ Antiporter In Echinoderm Gastrointestinal Epithelium, Zhenpeng Zhuang, Jeff Duerr, Gregory A. Ahearn
Faculty Publications - Department of Biological & Molecular Science
45Ca2+ uptake by purified brush-border membrane vesicles of starfish (Pycnopodia helianthoides) pyloric ceca was stimulated by an outwardly directed H+ gradient and this stimulation was enhanced by the simultaneous presence of an induced membrane potential (inside negative; K+/valinomycin). External amiloride (competitive inhibitor; Ki=660mmol l21) and a monoclonal antibody raised against proteins associated with the lobster (Homarus americanus) electrogenic 2Na+/1H+ antiporter both inhibited approximately half of the proton-gradient stimulated 45Ca2+ uptake. These results suggested that Ca2+ might be transported by the electrogenic antiporter and that the crustacean antibody was inhibitory to the exchange function in echinoderms, as was recently shown in …
Role Of The Invertebrate Electrogenic 2na+/H+ Antiporter In Monovalent And Divalent Cation Transport, Gregory A. Ahearn, Jeff Duerr, V. Pennington
Role Of The Invertebrate Electrogenic 2na+/H+ Antiporter In Monovalent And Divalent Cation Transport, Gregory A. Ahearn, Jeff Duerr, V. Pennington
Faculty Publications - Department of Biological & Molecular Science
In recent years, an electrogenic 2Na+/1H+ antiporter has been identified in a variety of invertebrate epithelial brush-border membranes of gut, kidney and gill tissues. The antiporter differs significantly in its physiological properties from the electroneutral 1Na+/1H+ antiporter proposed for vertebrate cells. In all invertebrate cells examined, the antiporter displayed a 2:1 transport stoichiometry, responded to an induced transmembrane potential and exhibited a high binding affinity for the divalent cation Ca2+, which acted as a competitive inhibitor of Na+ transport. A monoclonal antibody specific for the crustacean electrogenic antiporter inhibited 2Na+/1H+ exchange, but was without effect on Na+-dependent D-glucose transport. Immunoreactivity …