Fig. 7. Model of mAKAP complex. mAKAP associates with PKA, PDE4D3, PP2A and RyR at the cardiomyocyte NE. mAKAP is targeted to the NE by two spectrin-like repeat-containing domains (aa residues 772-915 and 915-1065) and binds PKA via an amphipathic helix at aa residues 2055-2072. mAKAP is associated with the N-terminal 568 aa of the RyR. PKA can phosphorylate RyR and PDE4D3, leading to increased ion channel and phosphodiesterase activity (a negative feedback loop; Dodge et al., 2001). PP2A may serve to reverse these phosphorylation events.
