Synaptic Ras-GTPase activating protein family Pleckstrin homology (PH) domain
The RasSynGAP family is composed of members: DAB2IP, nGAP, and SynGAP. Neuronal growth-associated proteins (nGAPs) are growth cone markers found in multiple types of neurons. There are many nGAPs including Cap1 (Adenylate cyclase-associated protein 1), Capzb (Capping protein (actin filament) muscle Z-line, beta), Clptm1 (Cleft lip and palate associated transmembrane protein 1), Cotl1 (Coactosin-like 1), Crmp1 (Collapsin response mediator protein 1), Cyfip1 (Cytoplasmic FMR1 interacting protein 1), Fabp7 (Fatty acid binding protein 7, brain), Farp2 (FERM, RhoGEF and pleckstrin domain protein 2), Gap43 (Growth associated protein 43), Gnao1 (Guanine nucleotide binding protein (G protein), alpha activating activity polypeptide O), Gnai2 (Guanine nucleotide binding protein (G protein), alpha inhibiting 2), Pacs1 (Phosphofurin acidic cluster sorting protein 1), Rtn1 (Reticulon 1), Sept2 (Septin 2), Snap25 (Synaptosomal-associated protein 25), Strap (Serine/threonine kinase receptor associated protein), Stx7 (Syntaxin 7), and Tmod2 (Tropomodulin 2). SynGAP, a neuronal Ras-GAP, has been shown display both Ras-GAP activity and Ras-related protein (Rap)-GAP activity. Saccharomyces cerevisiae Bud2 and GAP1 members CAPRI (Ca2+-promoted Ras inactivator) and RASAL (Ras-GTPase-activating-like protein) also possess this dual activity. Human DOC-2/DAB2-interacting protein (DAB2IP) is encoded by a tumor suppressor gene and a newly recognized member of the Ras-GTPase-activating family. DAB2IP is a critical component of many signal transduction pathways mediated by Ras and tumor necrosis factors including apoptosis pathways, and it is involved in the formation of many types of tumors. DAB2IP participates in regulation of gene expression and pluripotency of cells. It has been reported that DAB2IP was expressed in different tumor tissues. Little information is available concerning the expression levels of DAB2IP in normal tissues and cells, however, and no studies of its expression patterns during the development of human embryos have been reported. DAB2IP was expressed primarily in cell cytoplasm throughout the fetal development. The expression levels varied among tissues and different gestational ages. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.
Jiyao W et al.(2023). "The conserved domain database in 2023.",