AKAP1, also known as AKAP149 in human, AKAP121 in rat, or D-AKAP in mouse is a dual-specificity AKAP which can bind to both RI and RII subunits of PKA with similar affinity. Originally thought to be predominantly restricted to the mitochondria, growing evidence suggests that localization of AKAP1 can be regulated in part by alternative splicing events and that AKAP1 may be present in the endoplasmic reticulum-nuclear envelope membrane network. Peri-nuclear localization, along with the fact that AKAP1 interacts with RNA via one of two nucleotide-binding domains (K homology (KH) and Tudor) have lead some to suggest that AKAP1 may play a role in RNA metabolism. In addition to PKA-RI and -RII, AKAP1 directly interacts with PP1 in a phosphorylation dependent manner and nucleates a complex containing PP2Ac, PKA and RSK1 which modulates RSK1 localization and activity.