Figure 6.

Comparison of PLB phosphorylation catalyzed by PKA (a) and PKC (b) in the SR vesicles prepared from control and diabetic rat hearts. Cardiac SR vesicles were phosphorylated in the reaction mixture containing EGTA (2 mM), PKA catalytic subunit (10 nM), or a combination of PKC (9 μg ml⁻¹) and phosphatidylserine (18.7 μg ml⁻¹). The reaction was carried out for 3 min, and aliquots were then electrophoresed in polyacrylamide SDS gels. SR vesicles were boiled prior to gel electrophoresis. Autoradiograms of ³²P migrating with the 7-kDa bands, which were referred to as PLB, are shown in the upper panels. In each of the experiments, the PLB obtained from the control band is normalized as 1.0. Bars represent cumulative data of means±s.e.m. of three different preparations for PKA, and of four different preparations for PKC. ^*P<0.05.