Regulation of (Na++K+)-ATPase by inorganic phosphate: pH dependence and physiological implications |
| |
Authors: | W H Huang A Askari |
| |
Institution: | Department of Pharmacology, Medical College of Ohio, Toledo, OH 43699 USA |
| |
Abstract: | Inhibition of Na++K+-dependent ATPase activity by Pi was maximal in the pH range of 6.1-7, but decreased with increasing pH in the range of 7-8.5. Ki of Pi was 2.8 mM at pH 7.1, and 12 mM at pH 7.8. K+-dependent phosphorylation of the enzyme by Pi, which is thought to be responsible for inhibition of ATPase activity, also decreased with increasing pH. The data suggest that (a) previously observed requirement of high Pi concentrations for inhibition of ATPase activity and associated pump fluxes may have been due to high pH of the assays; (b) at normal values of intracellular pH the pump may be partially inhibited by intracellular Pi; and (c) this effect of Pi may be amplified or dampened with alterations in intracellular pH and ATP/Pi ratio. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|