Rho family members are small GTP binding proteins that serve as molecular switches for a number of biological processes. They cycle between active GTP-bound and inactive GDP-bound states. CDC42 is a Rho family protein that was identified in membranes of human platelets and placenta. It is the homologue of CDC42Sc, which regulates initiation of bud-site assembly in Saccharomyces cerevisiae. Similarly, CDC42 regulates the function of the mammalian actin cytoskeleton, allowing for efficient cytokinesis and cell morphogenesis. CDC42-interacting protein 4 (CIP4) was identified in a yeast-two hybrid screen for proteins that bind CDC42. Another variant of CIP4, CIP4/2, was identified that contains an extra 56 amino acids and has 71% identity with CIP4 (or CIP4/1). CIP4 contains a C-terminal SH3 domain and an N-terminal domain that is homologous to non-catalyitic motifs in the tyrosine kinase Fer. The mRNA expression of CIP4 is highest in skeletal muscle, heart, and placenta. Overexpression of CIP4 in Swiss 3T3 cells reduces the amount of stress fibers and leads to clustering of CIP4 to foci at the dorsal side of the cells. In addition, CIP4 binds the Rho-GTPase activating protein RICH and the cytoskeletal protein WASP. Coexpression of CIP4 and WASP in Cos-7 cells leads to WASP association with microtubules. Thus, CIP4 is involved in various protein-protein interactions associated with cytoskeletal dynamics.
This antibody is routinely tested by western blot analysis. Other applications were tested at BD Biosciences Pharmingen during antibody development only or reported in the literature.