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Dock Homology Region 2, a GEF domain, of Class A Dedicator of Cytokinesis proteins DOCK proteins are atypical guanine nucleotide exchange factors (GEFs) that lack the conventional Dbl homology (DH) domain. As GEFs, they activate small GTPases by exchanging bound GDP for free GTP. They are divided into four classes (A-D) based on sequence similarity and domain architecture; class A includes Dock1, 2 and 5. Class A DOCKs are specific GEFs for Rac. Dock1 interacts with the scaffold protein Elmo and the resulting complex functions upstream of Rac in many biological events including phagocytosis of apoptotic cells, cell migration and invasion. Dock2 plays an important role in lymphocyte migration and activation, T-cell differentiation, neutrophil chemotaxis, and type I interferon induction. Dock5 functions upstream of Rac1 to regulate osteoclast function. 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. This alignment model represents the DHR-2 domain of class A DOCKs, which contains the catalytic GEF activity for Rac and/or Cdc42. Class A DOCKs also contain an SH3 domain at the N-terminal region and a PxxP motif at the C-terminus. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",