A novel partner for the GTP‐bound forms of rho and rac

Abstract

Using the yeast two hybrid system and overlay assays we identified a putative rho/rac effector, citron, which interacts with the GTP‐bound forms of rho and rac1, but not with cdc42. Extensive homologies to known proteins were not observed. This 183 kDa protein contains a C₆H₂ zinc finger, a PH domain, and a long coiled‐coil forming region including 4 leucine zippers and the rho/rac binding site. We recently identified three others putative rho effectors characterized by a common rho binding motif. Citron does not share this motif and displays a distinctive protein organization, thus defining a separate class of rho partners.