Domain

Vav, PH domain (IPR037832)

Short name: PH_Vav

Overlapping homologous superfamilies

Domain relationships

Description

Vav acts as a guanosine nucleotide exchange factor (GEF) for Rho/Rac proteins. They control processes including T cell activation, phagocytosis, and migration of cells. The Vav subgroup of Dbl GEFs consists of three family members (Vav1, Vav2, and Vav3) in mammals [PMID: 10669724]. Vav1 is preferentially expressed in the hematopoietic system, while Vav2 and Vav3 are described by broader expression patterns [PMID: 26353933]. Mammalian Vav proteins consist of a calponin homology (CH) domain, an acidic region, a catalytic Dbl homology (DH) domain, a PH domain, a zinc finger cysteine rich domain (C1/CRD), and an SH2 domain, flanked by two SH3 domains. In invertebrates such as Drosophila and C. elegans, Vav is missing the N-terminal SH3 domain. The DH domain is involved in RhoGTPase recognition and selectivity and stimulates the reorganization of the switch regions for GDP/GTP exchange [PMID: 20141838]. The PH domain is implicated in directing membrane localization, allosteric regulation of guanine nucleotide exchange activity, and as a phospholipid-dependent regulator of GEF activity [PMID: 18511940]. Vavs bind RhoGTPases including Rac1, RhoA, and RhoG, while other members of the GEF family are specific for a single RhoGTPase. This promiscuity is thought to be a result of its CRD [PMID: 15850391].

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 [PMID: 22728242]. 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 [PMID: 15493994]. 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 [PMID: 14594214]. 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 [PMID: 22728242].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
CDD