The classical E2-P intermediate of (Na+ + K+)-ATPase dephosphorylates readily in the presence of K+ and is not affected by the addition of ADP. To determine the significane in the reaction cycle of (Na+ + K+)-ATPase of kinetically atypical phosphorylations of rat brain (Na+ + K+)-ATPase we compared these phosphorylated components with the classical E2-P intermediate of this enzyme by gel electrophoresis. When rat brain (Na+ + K+)-ATPase was phosphorylated in the presence of high concentrations of Na+ a proportion of the phosphorylated material formed was sensitive to ADP but resistant to K+. Similarly, if phosphorylation was carried out in the presence of Na+ and Ca2+ up to 300 pmol/mg protein of a K+-resistant, ADP-sensitive material were formed. If phosphorylation was from [γ-32P]CTP up to 800 pmol 32P/mg protein of an ADP-resistant, K+-sensitive phosphorylated matterial were formed. On gel electrophoresis these phosphorylated materials co-migrated with authentic Na+-stimulated, K+-sensitive, E2-P-phosphorylated intermediate of (Na+ + K+)-ATPase, supporting suggestions that they represent phosphorylated intermediates in the reaction sequence of this enzyme.
|Number of pages||9|
|Journal||BBA - Biomembranes|
|State||Published - Apr 21 1975|
Bibliographical noteFunding Information:
This work was supported by grants from the Michigan Heart Association, Grant H. L. 16055-01 from the National Institutes of Health, and General Research Support Grant NIH RR 05623-04 to the College of Veterinary Medicine, Michigan State University, from the National Institutes of Health. The authors would like to thank Mrs Annie Han and Mrs Marilyn Turnbow for excellent technical assistance.
ASJC Scopus subject areas
- Cell Biology