Cdc42 Background Information
Rho GTPases are molecular switches that regulate many essential cellular processes, including Actin dynamics, cell adhesion, cell-cycle progression and transcription. Cdc42, a small GTPase, regulates Actin polymerization, elongation of cell shape and cell signaling through interactions with many different downstream effector proteins. Most of these effector proteins contain a Cdc42-binding domain, called a CRIB domain. The evolutionarily conserved multi-protein complex, Cdc42-Par6-Par3-atypical protein kinase C (aPKC), is involved in the assembly of tight junctions and in polarization of Drosophila melanogaster epithelia. Cdc42- epithelial cells fail to elongate into a columnar cell shape and cannot maintain a monolayered epithelial structure. Also in Drosophila, growth cone pathfinding and filopodial dynamics are mediated separately by Cdc42 activation. In addition to regulating kinase activity, another important function of Cdc42 is to recruit Mbt (mushroom bodies tiny) to adherens junctions, suggesting a role for Mbt as a downstream effector of Cdc42 in photoreceptor cell morphogenesis.
