RAP1 GTPase Activating Protein 2 (RAP1GAP2)

RAP1GAP2 encodes a GTPase-activating protein that activates the small guanine-nucleotide-binding protein Rap1 in platelets. The protein interacts with synaptotagmin-like protein 1 and Rab27 and regulates secretion of dense granules from platelets at sites of endothelial damage. Multiple transcript variants encoding different isoforms have been found for this gene. Rap1GAP2 is expressed in at least 3 splice variants, 2 of which are detectable in platelets. Endogenous Rap1GAP2 protein partially colocalizes with Rap1 in human platelets. Phosphorylation of Rap1GAP2 by cGKI might mediate inhibitory effects of NO/cGMP on Rap1. Rap1GAP2 is the first GTPase-activating protein of Rap1 found in platelets and is likely to have an important regulatory role in platelet aggregation.