Invasion of the nucleotide snatchers: Structural insights into the mechanism of G protein GEFs

Article Abstract:

Replacement of GDP by GTP in the active G protein site requires the help of a guanine nucleotide exchange factor (GEF). GEFs are structurally diverse, and the structures of two new complexes have recently been elucidated, Ras with the CDC25 domain of Sos1, and ARF1 with the Sec7 domain of the S. cerevisiae protein Gea2. The new structures, together with previously determined GDP and GTP bound complexes of G proteins, offer an insight into the mechanism of activation by nucleotide exchange factors.

Observations, Nucleotides

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The structure of the G protein Heterotrimer G(sub i-alpha)-beta(sub 1)-gamma (sub 2)

Article Abstract:

The G protein heterotrimer formed by the alpha(sub i1), beta(sub 1) and gamma(sub 2) subunits is an asymmetrical molecule which is stabilized by interactions between the alpha and beta subunits. These interactions are necessary for the formation of the heterotrimer. The beta subunit forms a propeller domain containing seven motifs. There are two nonoverlapping contact sites between the alpha and beta subunits and an extended interface between beta and gamma.

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Structure of RGS4 bound to AIF4-activated Gialpha1: stabilization of the transition state for GTP hydrolysis

Article Abstract:

A study of the crystal structure of the RGS protein RGS4 complexed with Gialpha1 was conducted. The core domain binds to the three switch regions of Gialpha1 but does not contribute catalytic residues that interacts directly with either GDP or AIF4-. The findings indicate that RGS4 seems to catalyze rapid hydrolysis of GTP primarily through the stabilization of the switch regions of Gialpha1.

Proteins, Protein structure, Hydrolysis

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