Cytoplasmic protein NCK2 (NCK2) is a non-enzymatic adaptor protein composed of three SH3 (Src homology 3) domains and a C-terminal SH2 domain. There are two vertebrate NCK proteins, NCK1 and NCK2. NCK2 mediates Slit-induced cortical neurite outgrowth []. NCK2 interacts with focal adhesion kinase (FAK) and this interaction suggests a role of NCK2 in the modulation of cell motility []. It also interacts with DOCK1 [], LIMS1 [].
This entry represents the ELMO (EnguLfment and Cell MOtility) domain, which is found in a number of eukaryotic proteins involved in the cytoskeletal rearrangements required for phagocytosis of apoptotic cells and cell motility, including CED-12, ELMO-1 and ELMO-2. ELMO-1 and ELMO-2 are components of signalling pathways that regulate phagocytosis and cell migration and are mammalian orthologues of the Caenorhabditis elegans gene, ced-12 that is required for the engulfment of dying cells and cell migration. ELMO-1/2 act in association with DOCK1 and CRK. ELMO-1/2 interact with the SH3-domain of DOCK1 via an SH3-binding site to enhance the guanine nucleotide exchange factor (GEF) activity of DOCK1. ELMO-1/2 could be part of a complex with DOCK1 and Rac1 that could be required to activate Rac Rho small GTPases. Regulatory GTPases in the Ras superfamily employ a cycle of alternating GTP binding and hydrolysis, controlled by guanine nucleotide exchange factors and GTPase-activating proteins (GAPs), as essential features of their actions in cells. Within the Ras superfamily, the Arf family is composed of 30 members, including 22 Arf-like (Arl) proteins. The ELMO domain has been proposed to be a GAP domain for ARL2 and other members of the Arf family [].
DOCK family members are evolutionarily conserved guanine nucleotide exchange factors (GEFs) for Rho-family GTPases []. DOCK proteins are required during several cellular processes, such as cell motility and phagocytosis. The N-terminal SH3 domain of the DOCK proteins functions as an inhibitor of GEF, which can be relieved upon its binding to the ELMO1-3 adaptor proteins, after their binding to active RhoG at the plasma membrane [, ]. DOCK family proteins are categorised into four subfamilies based on their sequence homology: DOCK-A subfamily (DOCK1/180, 2, 5), DOCK-B subfamily (DOCK3, 4), DOCK-C subfamily (DOCK6, 7, 8), DOCK-D subfamily (DOCK9, 10, 11) []. This entry represents the C2 domain found in the Dock-C members. In addition to the C2 domain (also known as DHR-1 domain) and the DHR-2 domain, Dock-C members contain a functionally uncharacterised 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 Dock1 (also known as Dock180) and Dock4 have been shown to bind phosphatidylinositol-3, 4, 5-triphosphate (PtdIns(3,4,5)P3) [, , ].
DOCK family members are evolutionarily conserved guanine nucleotide exchange factors (GEFs) for Rho-family GTPases []. DOCK proteins are required during several cellular processes, such as cell motility and phagocytosis. The N-terminal SH3 domain of the DOCK proteins functions as an inhibitor of GEF, which can be relieved upon its binding to the ELMO1-3 adaptor proteins, after their binding to active RhoG at the plasma membrane [, ]. DOCK family proteins are categorised into four subfamilies based on their sequence homology: DOCK-A subfamily (DOCK1/180, 2, 5), DOCK-B subfamily (DOCK3, 4), DOCK-C subfamily (DOCK6, 7, 8), DOCK-D subfamily (DOCK9, 10, 11) []. This entry represents the C2 domain of the Dock-D members. In addition to the C2 domain (also known as the DHR-1 domain) and the DHR-2, Dock-D members contain a functionally uncharacterised domain and a PH 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 Dock1 (also known as Dock180) and Dock4 have been shown to bind phosphatidylinositol-3, 4, 5-triphosphate (PtdIns(3,4,5)P3). The PH domain broadly binds to phospholipids and is thought to be involved in targeting the plasma membrane [, , ].
DOCK family members are evolutionarily conserved guanine nucleotide exchange factors (GEFs) for Rho-family GTPases []. DOCK proteins are required during several cellular processes, such as cell motility and phagocytosis. The N-terminal SH3 domain of the DOCK proteins functions as an inhibitor of GEF, which can be relieved upon its binding to the ELMO1-3 adaptor proteins, after their binding to active RhoG at the plasma membrane [, ]. DOCK family proteins are categorised into four subfamilies based on their sequence homology: DOCK-A subfamily (DOCK1/180, 2, 5), DOCK-B subfamily (DOCK3, 4), DOCK-C subfamily (DOCK6, 7, 8), DOCK-D subfamily (DOCK9, 10, 11) []. This entry represents the C2 domain of the Dock-B members. Most of these members have been shown to be GEFs specific for Rac, although Dock4 has also been shown to interact indirectly with the Ras family GTPase Rap1, probably through Rap regulatory proteins. In addition to the C2 domain (also known as DHR-1 domain) and the DHR-2 domain, Dock-B members contain a SH3 domain upstream of the C2 domain and a proline-rich region downstream. 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 Dock1 (also known as Dock180) and Dock4 have been shown to bind phosphatidylinositol-3, 4, 5-triphosphate (PtdIns(3,4,5)P3)[, , ].
This entry represents engulfment and cell motility protein 2 (ELMO2) from vertebrates. ELMO2 is a scaffolding component of the Elmo-DOCK complex. Elmo2 and DOCK1 are essential for the rapid recruitment and spreading of E-cadherin, actin reorganisation, localised Rac and Rho GTPase activities, and the development of strong cell-cell adhesion []. ELMO2 interacts with Axl, a receptor tyrosine kinase, and this interaction contributes to cancer cell invasion and proliferation [].ELMO 1-3 are orthologues of the Caenorhabditis elegans ced-12, which is required for the engulfment of dying cells and cell migration []. They are cytoplasmic adaptor proteins that interact with DOCK family guanine nucleotide exchange factors (GEFs) to promote activation of the small GTPase Rac []. ELMO proteins interact with the SH3-domain of DOCKs via an SH3-binding site to enhance the GEF activity of DOCKs. Regulatory GTPases in the Ras superfamily employ a cycle of alternating GTP binding and hydrolysis, controlled by GEFs and GTPase-activating proteins (GAPs), as essential features of their actions in cells [, ].
