کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1984910 | 1539991 | 2005 | 15 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Gill microsomal (Na+,K+)-ATPase from the blue crab Callinectes danae: Interactions at cationic sites
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
بیوشیمی، ژنتیک و زیست شناسی مولکولی
زیست شیمی
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چکیده انگلیسی
Euryhaline crustaceans tolerate exposure to a wide range of dilute media, using compensatory, ion regulatory mechanisms. However, data on molecular interactions occurring at cationic sites on the crustacean gill (Na+,K+)-ATPase, a key enzyme in this hyperosmoregulatory process, are unavailable. We report that Na+ binding at the activating site leads to cooperative, heterotropic interactions that are insensitive to K+. The binding of K+ ions to their high affinity sites displaces Na+ ions from their sites. The increase in Na+ ion concentrations increases heterotropic interactions with the K+ ions, with no changes in K0.5 for K+ ion activation at the extracellular sites. Differently from mammalian (Na+,K+)-ATPases, that from C. danae exhibits additional NH4+ ion binding sites that synergistically activate the enzyme at saturating concentrations of Na+ and K+ ions. NH4+ binding is cooperative, and heterotropic NH4+ ion interactions are insensitive to Na+ ions, but Na+ ions displace NH4+ ions from their sites. NH4+ ions also displace Na+ ions from their sites. Mg2+ ions modulate enzyme stimulation by NH4+ ions, displacing NH4+ ion from its sites. These interactions may modulate NH4+ ion excretion and Na+ ion uptake by the gill epithelium in euryhaline crustaceans that confront hyposmotic media.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: The International Journal of Biochemistry & Cell Biology - Volume 37, Issue 12, December 2005, Pages 2521-2535
Journal: The International Journal of Biochemistry & Cell Biology - Volume 37, Issue 12, December 2005, Pages 2521-2535
نویسندگان
D.C. Masui, R.P.M. Furriel, E.C.C. Silva, F.L.M. Mantelatto, J.C. McNamara, H. Barrabin, H.M. Scofano, C.F.L. Fontes, F.A. Leone,