The WH2 (WASP-Homology 2, or Wiskott-Aldrich homology 2) domain is an ~18 amino acids actin-binding motif. This domain was first recognized as an essential element for the regulation of the cytoskeleton by the mammalian Wiskott-Aldrich syndrome protein (WASP) family. WH2 proteins occur in eukaryotes from yeast to mammals, in insect viruses, and in some bacteria. The WH2 domain is found as a modular part of larger proteins; it can be associated with the WH1 or EVH1 domain (see <PDOC50229>) and with the CRIB domain (see <PDOC50108>), and the WH2 domain can occur as a tandem repeat. The WH2 domain binds actin monomers and can facilitate the assembly of actin monomers into newly forming actin filaments [1,2,3,4].

Some proteins known to contain a WH2 domain:

• Mammalian Wiskott-Aldrich syndrome protein (WASP), a possible regulator of lymphocyte and platelet function. Defects in WASP are the cause of Wiskott- Aldrich syndrome (WAS), an X-linked recessive disease characterized by immune dysregulation and microthrombocytopenia. WASP proteins bind the actin nucleating protein complex Arp2/3.
• Mammalian N-WASP/WASL and WASF/SCAR/WAVE1-3, and yeast LAS17, which are also proteins from the WASP family that participate in the transduction of signals from the cell surface to the actin cytoskeleton.
• Baker's yeast Verprolin, a protein involved in cytoskeletal organization and cellular growth.
• Human WASP interacting protein (WASPIP/WIP), a WASP-, profilin- and actin-binding protein which induces actin polymerization and redistribution.
• Nuclear polyhedrosis virus (NPV) P61/78/83 capsid protein, which may be important for the persistence and survival of the virus.
• Fruit fly Spir(e) protein, an actin nucleation factor involved in the development of oocytes and embryos. Spir is conserved among metazoans.
• Mammalian metastasis suppressor 1 or Missing in Metastasis (MIM) protein, an actin-binding protein that may be related to cancer progression or tumor metastasis.

The profile we developed covers the entire WH2 domain.