The
Wiskott–Aldrich Syndrome protein (
WASp) is a 502-
amino acid protein expressed in cells of the
hematopoietic system. In the inactive state, WASp exists in an autoinhibited conformation with sequences near its
C-terminus binding to a region near its
N-terminus. Its activation is dependent upon
CDC42 and
PIP2 acting to disrupt this interaction, causing the WASp protein to 'open'. This exposes a domain near the WASp C-terminus that binds to and activates the
Arp2/3 complex. Activated Arp2/3
nucleates new F-
actin. WASp is the founding member of a gene family which also includes the broadly expressed
N-WASP (neuronal Wiskott–Aldrich Syndrome protein), and Scar.