دورية أكاديمية
Ca2+ and Zn2+ are Transported by the Electrogenic 2Na+/1H+ Antiporter in Echinoderm Gastrointestinal Epithelium
| العنوان: | Ca2+ and Zn2+ are Transported by the Electrogenic 2Na+/1H+ Antiporter in Echinoderm Gastrointestinal Epithelium |
|---|---|
| المؤلفون: | Zhuang, Zhenpeng, Duerr, Jeff, Ahearn, Gregory A. |
| المصدر: | Faculty Publications - Department of Biological & Molecular Science |
| بيانات النشر: | Digital Commons @ George Fox University |
| سنة النشر: | 1995 |
| المجموعة: | Digital Commons @ George Fox University |
| مصطلحات موضوعية: | brush-border membrane, calcium, zinc, antiport, electrogenic Ca2+/H+ exchange, channel, 2Na+/1H+ exchange, heavy metal, starfish, pyloric ceca, Echinodermata, Pycnopodia helianthoides, amiloride, Biology, Marine Biology |
| الوصف: | 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 crustacean epithelial brush-border membrane vesicles. Carrier-mediated 45Ca2+ influx by amiloride-sensitive and amiloride-insensitive systems displayed the following kinetic constants: (amiloride-sensitive) Kt=66±2 mmol l21; Jmax=0.173±0.002 pmol mg21 protein 8 s21; (amiloride-insensitive) Kt=18±0.3 mmol l21; Jmax=0.100±0.001 pmol mg21 protein 8 s21. Zn2+ was a mixed inhibitor of 45Ca2+ influx by carrier-mediated transport, displaying a Ki of 920mmol l21. Mn2+, Cu2+, Fe2+ and Mg2+ also inhibited 45Ca2+ uptake, but the mechanism(s) of inhibition by these other cations was not disclosed. An equilibrium shift experiment showed that both Na+ and Zn2+ were able to exchange with equilibrated 45Ca2+ in these vesicles, suggesting that both monovalent and divalent cations were able to enter pyloric cecal cells through a common carrier-mediated transport system. In addition, the echinoderm electrogenic system appeared to exhibit a molecular component recognized by the crustacean antibody that may imply a similar epitope in the two animals. |
| نوع الوثيقة: | text |
| وصف الملف: | application/pdf |
| اللغة: | unknown |
| العلاقة: | https://digitalcommons.georgefox.edu/bio_fac/7Test; https://digitalcommons.georgefox.edu/cgi/viewcontent.cgi?article=1006&context=bio_facTest |
| الإتاحة: | https://digitalcommons.georgefox.edu/bio_fac/7Test https://digitalcommons.georgefox.edu/cgi/viewcontent.cgi?article=1006&context=bio_facTest |
| رقم الانضمام: | edsbas.13F8A55B |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |