Figure 10.

Ca²⁺-Dependent Activation of Full-Length and N-Terminal Deletion Pumps.

Vanadate-sensitive ATPase activities of SCA1p (squares), SCA1p nt52 (diamonds), and SCA1p nt85 (circles) were determined at different concentrations of free Ca²⁺. Free Ca²⁺ concentration was determined using fluo-3, pentapotassium salt, and the Calcium Calibration Concentrated Buffer Kit, according to the manufacturer's instructions (Molecular Probes). Representative data from one of three similar experiments are shown.

(A) ATPase activities measured in the absence of calmodulin (open symbols).

(B) ATPase activities measured in the presence of 100 nM SCaM-1 (filled symbols).