b-Synemin is a cytoskeletal that also functions to targets PKA to specific subcellular locations, thus it also functions as an A-kinase anchoring protein (AKAP). We have recently confirmed that b-synemin is capable of binding both PKA type I and PKA type II using yeast two-hybrid, FACS-FRET, and co-immunoprecipitation analysis, which therefore classifies it as a dual AKAP. Most interestingly, our co-immunoprecipitation data also suggests that the binding of PKA type I to b-synemin only occurs only upon stimulation of the b-adrenergic pathway. Currently we are carrying out co-immunoprecipitation studies to determine the binding status of PKA type II and the catalytic subunit of PKA under both basal and stimulated conditions. These data are exciting because they suggest temporal compartmentalization of PKA type I and II at a single subcellular location, b-synemin.