Evolutionary expansion of CRIB-containing Cdc42 effector proteins

Cdc42,a small GTPase,regulates actinpolymerization and other signalingpathways through interaction with manydifferent downstream effector proteins.Most of these effector proteins contain a Cdc42-binding domain,called a CRIBdomain.Here,we describe the evolutionaryanalysis of these CRIB-containing proteinsin yeast,worms,flies and humans.Thenumber of CRIB-containing effectorproteins increases from yeast to humans,involving both an increase within familiesand the emergence of new families.Theseevolutionary changes correlate with thedevelopment of the more complexsignaling pathways present in higherorganisms.