Immunotitration of complex V in solubilized fractions from heart and muscle homogenates.

Conditions as described under Materials and Methods; panel A: complex V immunoblot obtained with one heart preparation and one muscle preparation; numbers above the lanes are the activity of the samples expressed as nmoles ATP hydrolyzed per minute. Panel B: densitometric signal intensity expressed in arbitrary units plotted against complex V activity; (■) heart, (□) muscle. Panel C: for each complex V activity, signal intensity from muscle preparation plotted against signal intensity from heart preparation (data drawn from results in Panel B); diagonal = dashed straight line. The slope of the graph (= 0.36) gives the ratio of complex V content between muscle and heart preparations at a given enzyme activity.