?
RA and RhoGAP domain-containing protein Pleckstrin homology PH domain RARhoGAP (also called Rho GTPase-activating protein 20 and ARHGAP20 ) is thought to function in rearrangements of the cytoskeleton and cell signaling events that occur during spermatogenesis. RARhoGAP was also shown to be activated by Rap1 and to induce inactivation of Rho, resulting in the neurite outgrowth. Recent findings show that ARHGAP20, even although it is located in the middle of the MDR on 11q22-23, is expressed at higher levels in chronic lymphocytic leukemia patients with 11q22-23 and/or 13q14 deletions and its expression pattern suggests a functional link between cases with 11q22-23 and 13q14 deletions. The mechanism needs to be further studied. RARhoGAP contains a PH domain, a Ras-associating domain, a Rho-GAP domain, and ANXL repeats. 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.",