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Publication Abstract from PubMed

Regulation of protein interaction domains is required for cellular signaling dynamics. Here, we show that the PDZ protein interaction domain from the cell polarity protein Par-6 is regulated by the Rho GTPase Cdc42. Cdc42 binds to a CRIB domain adjacent to the PDZ domain, increasing the affinity of the Par-6 PDZ for its carboxy-terminal ligand by approximately 13-fold. Par-6 PDZ regulation is required for function as mutational disruption of Cdc42-Par-6 PDZ coupling leads to inactivation of Par-6 in polarized MDCK epithelial cells. Structural analysis reveals that the free PDZ domain has several deviations from the canonical PDZ conformation that account for its low ligand affinity. Regulation results from a Cdc42-induced conformational transition in the CRIB-PDZ module that causes the PDZ to assume a canonical, high-affinity PDZ conformation. The coupled CRIB and PDZ architecture of Par-6 reveals how simple binding domains can be combined to yield complex regulation.

Cdc42 regulates the Par-6 PDZ domain through an allosteric CRIB-PDZ transition.,Peterson FC, Penkert RR, Volkman BF, Prehoda KE Mol Cell. 2004 Mar 12;13(5):665-76. PMID:15023337^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.