SIPA1-like proteins share sequence similarity with signal-induced proliferation-associated protein 1 (SIPA1), which is a GTPase activator for the nuclear Ras-related regulatory proteins Rap1 and Rap2 [, ]. This entry represents SIPA1L1 (also known as SPAR), which has been identified as a Rap-specific GTPase-activating protein. SPAR is a postsynaptic regulator of synaptic morphology and function []. It interacts with the scaffold protein PSD-95 and forms a complex with PSD-95 and NMDA receptors in brain. It regulates F-Actin organisation and recruits PSD-95 to F-actin [].
This domain is found in C-terminal of the signal-induced proliferation-associated 1-like (SIPA1L) proteins, including SIPA1L 1-3 from humans. SIPA1Ls shares protein sequence similarity with signal-induced proliferation-associated protein 1 (SIPA1), which is a GTPase activator for the nuclear Ras-related regulatory proteins Rap1 and Rap2 [, ]. In rats SIPA1L1 (also known as SPAR) has been identified as a Rap-specific GTPase-activating protein [].
