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TBC1 domain family member 2A pleckstrin homology (PH) domain TBC1D2A (also called PARIS-1/Prostate antigen recognized and identified by SEREX 1 and ARMUS) contains a PH domain and a TBC-type GTPase catalytic domain. TBC1D2A integrates signaling between Arf6, Rac1, and Rab7 during junction disassembly. Activated Rac1 recruits TBC1D2A to locally inactivate Rab7 via its C-terminal TBC/RabGAP domain and facilitate E-cadherin degradation in lysosomes. The TBC1D2A PH domain mediates localization at cell-cell contacts and coprecipitates with cadherin complexes. 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.",