?
Active breakpoint cluster region-related protein pleckstrin homology (PH) domain The ABR protein contains multiple domains including a RhoGEF domain, a PH domain, a C1 domain, a C2 domain, and a C-terminal RhoGAP domain. It is related to a slightly larger protein, BCR, which is structurally similar, but has an additional N-terminal kinase domain. ABR has GAP activity for both Rac and Cdc42. It promotes the exchange of RAC or CDC42-bound GDP by GTP, thereby activating them. It is highly enriched in the brain and found to a lesser extent in heart, lung and muscle. 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.",