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Dock Homology Region 2, a GEF domain, of Dedicator of Cytokinesis proteins DOCK proteins comprise a family of atypical guanine nucleotide exchange factors (GEFs) that lack the conventional Dbl homology (DH) domain. As GEFs, they activate the small GTPases Rac and Cdc42 by exchanging bound GDP for free GTP. They are also called the CZH (CED-5, Dock180, and MBC-zizimin homology) family, after the first family members identified. Dock180 was first isolated as a binding partner for the adaptor protein Crk. The Caenorhabditis elegans protein, Ced-5, is essential for cell migration and phagocytosis, while the Drosophila ortholog, Myoblast city (MBC), is necessary for myoblast fusion and dorsal closure. DOCKs are divided into four classes (A-D) based on sequence similarity and domain architecture: class A includes Dock1 (or Dock180), 2 and 5; class B includes Dock3 and 4; class C includes Dock6, 7, and 8; and class D includes Dock9, 10 and 11. All DOCKs contain two homology domains: the DHR-1 (Dock homology region-1), also called CZH1, and DHR-2 (also called CZH2 or Docker). This alignment model represents the DHR-2 domain of DOCK proteins, which contains the catalytic GEF activity for Rac and/or Cdc42. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",