title: WH2 domain: a small, versatile adapter for actin monomers.
abstract: The actin cytoskeleton plays a central role in many cell biological processes. The structure and dynamics of the actin cytoskeleton are regulated by numerous actin-binding proteins that usually contain one of the few known actin-binding motifs. WH2 domain (WASP homology domain-2) is a approximately 35 residue actin monomer-binding motif, that is found in many different regulators of the actin cytoskeleton, including the beta-thymosins, ciboulot, WASP (Wiskott Aldrich syndrome protein), verprolin/WIP (WASP-interacting protein), Srv2/CAP (adenylyl cyclase-associated protein) and several uncharacterized proteins. The most highly conserved residues in the WH2 domain are important in beta-thymosin's interactions with actin monomers, suggesting that all WH2 domains may interact with actin monomers through similar interfaces. Our sequence database searches did not reveal any WH2 domain-containing proteins in plants. However, we found three classes of these proteins: WASP, Srv2/CAP and verprolin/WIP in yeast and animals. This suggests that the WH2 domain is an ancient actin monomer-binding motif that existed before the divergence of fungal and animal lineages.
authors.affiliation: Program in Cellular Biotechnology, Institute of Biotechnology, Viikki Biocenter, P.O. Box 56, University of Helsinki, 00014 Helsinki, Finland.
authors.forename: Eija
authors.initials: E
authors.lastname: Paunola
authors.forename: Pieta K
authors.initials: PK
authors.lastname: Mattila
authors.forename: Pekka
authors.initials: P
authors.lastname: Lappalainen
mesh_terms: D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000378:metabolism; D004330:Drosophila; D029721:Drosophila Proteins; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins; D010802:Phylogeny; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013947:Thymosin / Q000737:chemistry / Q000378:metabolism; D014923:Wiskott-Aldrich Syndrome; D051316:Wiskott-Aldrich Syndrome Protein
chemical_list: D000199:Actins; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D011506:Proteins; C495767:WAS protein, human; D051316:Wiskott-Aldrich Syndrome Protein; C414741:cib protein, Drosophila; D013947:Thymosin