Enables guanyl-nucleotide exchange factor activity; kinase binding activity; and small GTPase binding activity. Acts upstream of or within Ras protein signal transduction and regulation of GTPase activity. Located in perinuclear region of cytoplasm. Part of guanyl-nucleotide exchange factor complex. Is expressed in thymus primordium. Human ortholog(s) of this gene implicated in hypertension. Orthologous to human RASGRP3 (RAS guanyl releasing protein 3). [provided by Alliance of Genome Resources, Apr 2022]