Functions as a calcium-regulated nucleotide exchange factor activating both Ras and RAC1 through the exchange of bound GDP for GTP. Preferentially activates HRAS in vivo compared to RRAS based on their different types of prenylation. Functions in synaptic plasticity by contributing to the induction of long term potentiation. Homooligomer and heterooligomer with RASGRF1. Interacts with Ras and RAC1. Interacts in a calcium-dependent manner with calmodulin. Interacts with EPB49 and probably CDK5R1. Interacts with the AMPA receptor through GRIA1. Interacts with microtubules. Translocates to membranes when activated. Found both at cell periphery and along the axon of neurons (By similarity). Expressed in brain in the nucleus of the solitary tract. Not observed in the hippocampus (at protein level). Expression increases in the cortex from birth to adulthood. The Ras-GEF domain and the N-terminal Ras-GEF domain form a Ras-binding site and mediate Ras activation. The IQ domain mediates the calcium-dependent interaction with calmodulin but is dispensable for the Ras-GEF activity. The DH (DBL-homology) domain mediates interaction with RASGRF1 and probably EPB49 and is required for RAC1 activation. Phosphorylated by CDK5; down-regulates RASGRF2-mediated RAC1 activation. Ubiquitinated upon interaction with Ras. Ubiquitination leads to degradation through the 26S proteasome. Mice do not display overt phenotype. Preferentially activates HRAS in vivo compared to R-RAS based on their different types of prenylation.