Figure 5. AKAP mediated effect is isoform dependent. (A) Mean AKAP79 effect on current amplitude recorded for CaV1.2 wt and a leucine zipper deletion mutant CaV1.2-LZ. Note that AKAP79 does not increase current amplitudes of CaV1.2 channels lacking the leucine zipper. Right panel: western blot of in vitro binding assay between AKAP79 and the C-terminal domain of CaV1.2 lacking the leucine zipper motif. Note that the CaV1.2-LZ C-terminus region cannot bind AKAP79 in vitro. (B) Effect of AKAP18 on the CaV1.2 current amplitude. AKAP18 does not mediate an increase in current amplitude, but acts as a dominant negative to suppress the AKAP79 mediated current enhancement.