G-protein-coupled receptor kinase-interacting protein 1 (GIT1) is enriched in both presynaptic and postsynaptic terminals and after phosphorylation is targeted to the synapse by binding to cytoplasmic protein GRB4 (NCK2 aka GRB4). GRB4 binds by its SH2 domain to Tyr392 (Human Tyr383) in the synaptic localization domain (SLD) of GIT1. GIT1 acts as an adapter protein by providing docking site for beta-PIX (PAK interacting exchange factor) and serves to localize Rac activity (Segura et al. 2007, Zhang et al. 2003).