Rhodopsin kinase: Two mAbs binding near the carboxyl terminus cause time-dependent inactivation

Two mAbs generated against rhodopsin kinase (RK) were characterized for the ir epitopes. Both antibodies recognize short peptide sequences, overlapping but distinct, close to the carboxyl terminus, Binding of RK to the antibod ies is stow. Attempts were made to use the antibodies immobilized on protei n A-Sepharose beads to bind and purify the enzyme. Time-dependent inactivat ion of the enzyme occurred after its binding to the antibodies. Studies usi ng different conditions to maintain the enzyme in the active form during bi nding or to reactivate the purified inactivated enzyme were unsuccessful.