Src Homology 3 domain of Class B Dedicator of Cytokinesis 4
Dock4 is a class B DOCK and is an atypical guanine nucleotide exchange factor (GEF) that lacks the conventional Dbl homology (DH) domain. It plays a role in regulating dendritic growth and branching in hippocampal neurons, where it is highly expressed. It may also regulate spine morphology and synapse formation. Dock4 activates the Ras family GTPase Rap1, probably indirectly through interaction with Rap regulatory proteins. All DOCKs contain two homology domains: the DHR-1 (Dock homology region-1), also called CZH1 (CED-5, Dock180, and MBC-zizimin homology 1), and DHR-2 (also called CZH2 or Docker). The DHR-1 domain binds phosphatidylinositol-3,4,5-triphosphate while DHR-2 contains the catalytic activity for Rac and/or Cdc42. Class B DOCKs also contain an SH3 domain at the N-terminal region and a PxxP motif at the C-terminus. The SH3 domain of Dock4 binds to DHR-2 in an autoinhibitory manner; binding of the scaffold protein Elmo to the SH3 domain of Dock4 exposes the DHR-2 domain and promotes GEF activity. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.
Feature 1:ELMO interaction site [polypeptide binding site]
Evidence:
Comment:based on the crystal structure of human Dock2-Elmo1 complex
Comment:ELMO = Engulfment and Motility
Comment:Class A/B DOCKs bind Elmo, a scaffold protein that promotes GEF activity of DOCKs by releasing DHR-2 autoinhibition by the intramolecular SH3 domain.
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