FUNCTION: Effector protein for Rho-type GTPases, providing a link with the Arp2/3 complex that regulates the structure and dynamics of the actin cytoskeleton. Important for efficient actin polymerization. Possible regulator of lymphocyte and platelet function.
SUBUNIT STRUCTURE: Binds to CDC42, RAC, NCK, FYN, SRC kinase FGR, BTK, ABL, PSTPIP1, WIP, and to the p85 subunit of PLC-gamma. Binds the Arp2/3 complex.
SUBCELLULAR LOCATION: Cytoplasm › cytoskeleton.
TISSUE SPECIFICTY: Expressed predominantly in the thymus. Also found, to a much lesser extent, in the spleen. Ref.1
DOMIAN: The WH1 (Wasp homology 1) domain may bind a Pro-rich ligand.
The CRIB (Cdc42/Rac-interactive-binding) region binds to the C-terminal WH2 domain in the autoinhibited state of the protein. Binding of Rho-type GTPases to the CRIB induces a conformation change and leads to activation.
INVOLVEMENT IN DISEASE: Defects in WAS are the cause of Wiskott-Aldrich syndrome (WAS) [MIM:301000]; also known as eczema-thrombocytopenia-immunodeficiency syndrome. WAS is an X-linked recessive immunodeficiency characterized by eczema, thrombocytopenia, recurrent infections, and bloody diarrhea. Death usually occurs before age 10.
Defects in WAS are the cause of thrombocytopenia type 1 (THC1) [MIM:313900]. Thrombocytopenia is defined by a decrease in the number of platelets in circulating blood, resulting in the potential for increased bleeding and decreased ability for clotting.
Defects in WAS are a cause of X-linked severe congenital neutropenia (XLN) [MIM:300299]. XLN is an X-linked immunodeficiency syndrome characterized by recurrent major bacterial infections, severe congenital neutropenia, and monocytopenia.
SEQUENCE SIMILARITIES: Contains 1 CRIB domain.
Contains 1 WH1 domain.
Contains 1 WH2 domain.