SOLUTION STRUCTURE OF THE AUTOINHIBITED CONFORMATION OF WASP
[WASP_HUMAN] 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 neutropenia severe congenital X-linked (XLN) [MIM:300299]. XLN is an immunodeficiency syndrome characterized by recurrent major bacterial infections, severe congenital neutropenia, and monocytopenia.
[WASP_HUMAN] Effector protein for Rho-type GTPases. Regulates actin filament reorganization via its interaction with the Arp2/3 complex. Important for efficient actin polymerization. Possible regulator of lymphocyte and platelet function. Mediates actin filament reorganization and the formation of actin pedestals upon infection by pathogenic bacteria.  
Publication Abstract from PubMed
The Rho-family GTPase, Cdc42, can regulate the actin cytoskeleton through activation of Wiskott-Aldrich syndrome protein (WASP) family members. Activation relieves an autoinhibitory contact between the GTPase-binding domain and the carboxy-terminal region of WASP proteins. Here we report the autoinhibited structure of the GTPase-binding domain of WASP, which can be induced by the C-terminal region or by organic co-solvents. In the autoinhibited complex, intramolecular interactions with the GTPase-binding domain occlude residues of the C terminus that regulate the Arp2/3 actin-nucleating complex. Binding of Cdc42 to the GTPase-binding domain causes a dramatic conformational change, resulting in disruption of the hydrophobic core and release of the C terminus, enabling its interaction with the actin regulatory machinery. These data show that 'intrinsically unstructured' peptides such as the GTPase-binding domain of WASP can be induced into distinct structural and functional states depending on context.
Autoinhibition and activation mechanisms of the Wiskott-Aldrich syndrome protein.,Kim AS, Kakalis LT, Abdul-Manan N, Liu GA, Rosen MK Nature. 2000 Mar 9;404(6774):151-8. PMID:10724160
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.