Figure 3.
Assessment of myocardial βARK1 levels and activity. (A) βARK1 protein levels of myocardial extracts were determined by protein immunoblotting. Shown is a representative experiment with two hearts from each gene-targeted mouse. Similar results were obtained in two more hearts in each group. βARK1 protein levels were ≈2-fold higher in the MLP−/− hearts compared with MLP+/+ hearts (P < 0.05) whereas myocardial βARK1 levels in the MLP−/−/βARKct hearts were not significantly different than wild-type hearts. (B) Rhodopsin-enriched rod outer segment membranes were used as a substrate for membrane myocardial GRK activity and 32P incorporation was quantified from dried gels. The data represent a sample size of four to six hearts in each group. ∗, P < 0.05 vs. MLP+/+; #, P < 0.03 vs. MLP−/−.