Inhibition of Ca2+ uptake into fragmented sarcoplasmic reticulum by antibodies against purified Ca2+, Mg2+-dependent ATPase.

Rabbit antiserum was prepared against a partially purified Ca2+, Mg2+-dependent ATPase EC 3.6.1.3] of the SR isolated from chicken skeletal muscle. The gamma-globulin fraction of antiserum contained antibodies which combined with the purified ATPase and the SR vesicles. Binding of the antibodies strongly inhibited active transport of Ca2+ ions into the SR, but not passive leakage of Ca2+ ions from the SR. The antibodies scarcely affected the ATPase activity.