A A-Kinase Anchoring Protein (AKAP)

Classical physiological experiments identified cAMP as a diffusible intracellular secondary messenger capable of activating cAMP-dependent protein kinase (PKA). These studies defined hormoneand location-specific patterns of PKA activation, suggesting that PKA signaling was compartmentalized. For example, in perfused rat cardiomyocytes, adrenergic stimulation selectively activates a pool of PKA isolated from certain fractions, while prostanoids predominately activate cytosolic PKA (Scott et al. 2013). The first AKAP to be identified, microtubuleassociated protein 2 (MAP2), was copurified with the PKA regulatory subunit subtype II (RII) from rat brain extracts. Over 50 additional AKAP family members have subsequently been identified (Fraser and Scott 1999; Scott et al. 2013). AKAPs are structurally diverse and share little primary sequence similarity, but are functionally similar and are classified by their ability to copurify with PKA catalytic activity from tissues (Langeberg and Scott 2015).