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Wiskott-Aldrich Syndrome Homology (WASP) region 2 (WH2 motif), and similar proteins This family contains the Wiskott-Aldrich syndrome protein (WASP)-homology domain 2 (WH2) as well as thymosin-beta (Tbeta; also called beta-thymosin or betaT) domains that are small, widespread intrinsically disordered actin-binding peptides displaying significant sequence variability and different regulations of actin self-assembly in motile and morphogenetic processes. These WH2/betaT peptides are identified by a central consensus actin-binding motif LKKT/V flanked by variable N-terminal and C-terminal extensions; the betaT shares a more extended and conserved C-terminal half than WH2. These single or repeated domains are found in actin-binding proteins (ABPs) such as the hematopoietic-specific protein WASP, its ubiquitously expressed ortholog neural-WASP (N-WASP), WASP-interacting protein (WAS/WASL-interacting protein family members 1 and 2), and WASP-family verprolin homologous protein (WAVE/SCAR) isoforms: WAVE1, WAVE2, and WAVE3. Also included are the WH2 domains found in inverted formin FH2 domain-containing protein (INF2), Cordon bleu (Cobl) protein, vasodilator-stimulated phosphoprotein (VASP) homology protein and actobindin (found in amoebae). These ABPs are commonly multidomain proteins that contain signaling domains and structurally conserved actin-binding motifs, the most important being the WH2 domain motif through which they bind actin in order to direct the location, rate, and timing for actin assembly in the cell into different structures, such as filopodia, lamellipodia, stress fibers, and focal adhesions. The WH2 domain motif is one of the most abundant actin-binding motifs in Wiskott-Aldrich syndrome proteins (WASPs) where they activate Arp2/3-dependent actin nucleation and branching in response to signals mediated by Rho-family GTPases. The thymosin beta (Tbeta) domains in metazoans act in cells as major actin-sequestering peptides; their complex with monomeric ATP-actin (G-ATP-actin) cannot polymerize at either filament (F-actin) end. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",