Activation of Rho GTPases by DOCK Exchange Factors Is Mediated by a Nucleotide Sensor

Abstract

Crystal Clear Guanine nucleotide exchange factors stimulate exchange of guanine diphosphate (GDP) for guanine triphosphate (GTP) and activate small guanosine triphosphatases (GTPases) required for the regulation of many biological processes. Yang et al. (p. 1398 ) provide a detailed picture of the complete catalytic cycle by which a guanine nucleotide exchange factor, DOCK9, activates the small GTPase, Cdc42. A small region of DOCK9 appears to sense whether GTP or GDP is bound to Cdc42 in a mechanism that is distinct from that observed for other GTPases.