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C2 domains found in Dedicator Of CytoKinesis (Dock) class C proteins Dock-C is one of 4 classes of Dock family proteins. The members here include: Dock6/Zir1, Dock7/Zir2, and Dock8/Zir3. Dock-C members are GEFs for both Rac and Cdc42. In addition to the C2 domain (AKA Dock homology region (DHR)-1, CED-5, Dock180, MBC-zizimin homology (CZH) 1) and the DHR-2 (AKA CZH2, or Docker), which all Dock180-related proteins have, Dock-C members contain a functionally uncharacterized domain upstream of the C2 domain. DHR-2 has the catalytic activity for Rac and/or Cdc42, but is structurally unrelated to the DH domain. The C2/DHR-1 domains of Dock180 and Dock4 have been shown to bind phosphatidylinositol-3, 4, 5-triphosphate (PtdIns(3,4,5)P3). The C2 domain was first identified in PKC. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",