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SH3 domain-binding protein 2 Pleckstrin homology (PH) domain SH3BP2 (the gene that encodes the adaptor protein 3BP2), HD, ITU, IT10C3, and ADD1 are located near the Huntington's Disease Gene on Human Chromosome 4pl6.3. SH3BP2 lies in a region that is often missing in individuals with Wolf-Hirschhorn syndrome (WHS). Gain of function mutations in SH3BP2 causes enhanced B-cell antigen receptor (BCR)-mediated activation of nuclear factor of activated T cells (NFAT), resulting in a rare, genetic disorder called cherubism. This results in an increase in the signaling complex formation with Syk, phospholipase C-gamma2 (PLC-gamma2), and Vav1. It was recently discovered that Tankyrase regulates 3BP2 stability through ADP-ribosylation and ubiquitylation by the E3-ubiquitin ligase. Cherubism mutations uncouple 3BP2 from Tankyrase-mediated protein destruction, which results in its stabilization and subsequent hyperactivation of the Src, Syk, and Vav signaling pathways. SH3BP2 is also a potential negative regulator of the abl oncogene. 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.",