Site-specific monoubiquitination activates Ras by impeding GTPase-activating protein function.

ABSTRACT: Cell growth and differentiation are controlled by growth factor receptors coupled to the GTPase Ras. Oncogenic mutations disrupt GTPase activity, leading to persistent Ras signaling and cancer progression. Recent evidence indicates that monoubiquitination of Ras leads to Ras activation. Mutation of the primary site of monoubiquitination impairs the ability of activated K-Ras (one of the three mammalian isoforms of Ras) to promote tumor growth. To determine the mechanism of human Ras activation, we chemically ubiquitinated the protein and analyzed its function by NMR, computational modeling and biochemical activity measurements. We established that monoubiquitination has little effect on the binding of Ras to guanine nucleotide, GTP hydrolysis or exchange-factor activation but severely abro

SUBMITTER: Baker R 

PROVIDER: S-EPMC3537887 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature