WASP interacting proteins (WIP) family includes WIPF1 (WIP), WIPF2 (WIRE,WICH) and WIPF3 (CR16, corticosteroids and regional expression-16). WIPs share a specific proline rich sequence that interacts with the WH1 domain of WASP and N-WASP (WASL). WIPs form heterocomplexes with WASPs and may contribute to the WASP protein stability (Aspenstrom 2002, Kato et al. 2002, Ho et al. 2001, Moreau et al. 2000).
SH3 domain containing adaptor proteins like GRB2 (Carlier et al. 2000), NCK (Rohatgi et al. 2001) and WISH (DIP/SPIN90) (Fukuoka et al. 2001) bind to the proline rich domain in WASPs and activate the ARP2/3 complex. By binding simultaneously to N-WASP and the ARP2/3 complex, GRB2 works synergistically with CDC42 in the activation of ARP2/3 complex-mediated actin assembly (Carlier et al. 2000).