Acid-induced uncoupling of sarcoplasmic reticulum membranes is reversed by reconstitution

Mild acid treatment of sarcoplasmic reticulum membranes results in a first order decline in calcium transport activity while calcium stimulated ATPase activity remains unimpaired (Berman, M.C., McIntosh, D.B. and Kench, K.E. (1977) J. Biol. Chem. $\text{252}$ 994–1001). This uncoupling is apparently irreversible. Acid inactivated sarcoplasmic reticulum membranes, solubilized with Triton X-100 and reconstituted by passage through a Bio-Bead column, reactivated 80% of the calcium transport activity when compared with untreated, control reconstituted SR vesicles. It is suggested that the inactivated conformation of the (Ca²⁺, Mg²⁺-)ATPase is constrained by lipid-protein interactions.