title: Crystal structure of a G-protein beta gamma dimer at 2.1A resolution.
abstract: Many signalling cascades use seven-helical transmembrane receptors coupled to heterotrimeric G proteins (G alpha beta gamma) to convert extracellular signals into intracellular responses. Upon nucleotide exchange catalysed by activated receptors, heterotrimers dissociate into GTP-bound G alpha subunits and G beta gamma dimers, either of which can modulate many downstream effectors. Here we use multiwavelength anomalous diffraction data to solve the crystal structure of the beta gamma dimer of the G protein transducin. The beta-subunit is primarily a seven-bladed beta-propeller that is partially encircled by an extended gamma-subunit. The beta-propeller, which contains seven structurally similar WD repeats, defines the stereochemistry of the WD repeat and the probable architecture of all WD-repeat-containing domains. The structure details interactions between G protein beta- and gamma-subunits and highlights regions implicated in effector modulation for the conserved family of G protein beta gamma dimers.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, USA.
authors.forename: J
authors.initials: J
authors.lastname: Sondek
authors.forename: A
authors.initials: A
authors.lastname: Bohm
authors.forename: D G
authors.initials: DG
authors.lastname: Lambright
authors.forename: H E
authors.initials: HE
authors.lastname: Hamm
authors.forename: P B
authors.initials: PB
authors.lastname: Sigler
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017948:Retinal Rod Photoreceptor Cells / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D015293:Transducin / Q000737:chemistry*
chemical_list: D015293:Transducin