GAP1 (GTPase-activating protein 1) family members include RASA2 (GAP1m), RASAL (RASAL1), GAP1(IP4BP or RASA3), and CAPRI (RASA4). They all display Ras GAP activity. With the exception of RASA2, they all possess an arginine finger-dependent GAP activity on Rap1 [, ]. They contain N-terminal tandem C2 domain repeats, a centrally located Ras-GAP domain, and a PH (pleckstrin homology) domain containing a Btk motif [].This entry represents the PH domain of Ras GTPase-activating protein 3 (RASA3, also known as GAP1 or IP4BP). The RASA3 PH domain binds to phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3) and I(1,3,4,5)P4 []. Its C2 domains, like those of RASA2 (GAP1M), do not contain the C2 motif that is known to be required for calcium-dependent phospholipid binding [].
