Premium
Reconstitution of the sodium pump from protein and phosphatidylserine: features of ouabain binding
Author(s) -
Chipperfield A. R.,
Whittam R.
Publication year - 1973
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1973.sp010198
Subject(s) - phosphatidylserine , ouabain , sodium pump , sodium , chemistry , biophysics , biochemistry , biology , membrane , phospholipid , organic chemistry
1. A study has been made of ATP splitting and ouabain binding to the sodium pump reconstituted from protein and phosphatidylserine. 2. Ouabain was bound to protein alone, but when phosphatidylserine was added, binding was increased threefold. The stimulation resembled the course of activation of sodium‐dependent ATPase activity. 3. EGTA partly simulated the activation of ATPase by phosphatidylserine but did not enhance binding. 4. The dissociation constant for the enzyme‐ouabain complex was 3·5 × 10 −8 M . The turnover number (2,000 molecules of ATP per minute) and the number of receptor sites (3·8 × 10 13 per mg protein) were calculated. 5. The results provide further evidence of the involvement of phosphatidylserine in the action of the sodium pump.