The calcium ATPase of sarcoplasmic reticulum is inhibited by one Ca2+ ion.
Inhibition by calcium of the steady-state turnover of the calcium ATPase from sarcoplasmic reticulum of rabbit muscle follows a Hill slope of 0.8 +/- 0.2 (pH 7.0, 0.1 M KCl, varying [Mg2+] and 2 microM A23187 ionophore). It is concluded that dissociation of the two Ca2+ ions from E-P.Ca2 is sequential and that the inhibition arises from the binding of one Ca2+ to A-P.Ca1.
Khananshvili
D
D
Graduate Department of Biochemistry, Brandeis University, Waltham, MA 02254.
Myung
J
J
Kolouch
R
R
Jencks
W P
WP
D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D001667:Binding, Competitive; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D008274:Magnesium / Q000494:pharmacology; D008433:Mathematics; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*
D000001:Calcimycin; D000252:Calcium-Transporting ATPases; D008274:Magnesium; D002118:Calcium