GTPase-activating protein for RAC1 and perhaps Cdc42, but not for RhoA small GTPase. May attenuate RAC1 signaling in neurons. Homodimer (Probable). Forms a heterooligomer with SRGAP1 and SRGAP2 through its F-BAR domain. Interacts with WASF1. Probably interacts with ROBO1. Interacts with FASLG. Highly expressed in adult and fetal brain. Expressed at low levels in kidney. Isoform 3 is expressed in the kidney but is absent in the brain. The F-BAR domain mediates oligomerization, binds membranes, and induces plasma membrane protrusions. A chromosomal aberration involving SRGAP3 is found in a patient with severe idiopathic intellectual disability (PubMed:12195014). Translocation t(X;3)(p11.2;p25) (PubMed:12195014).