2hlb
From Proteopedia
A Structural Basis for Nucleotide Exchange on G-alpha-i Subunits and Receptor Coupling Specificity
Overview
Heterotrimeric G proteins are molecular switches that relay information intracellularly in response to various extracellular signals. How ligand-activated G protein-coupled receptors act at a distance to exert exchange activity on the Galpha nucleotide binding pocket is poorly understood. Here we describe the synergistic action of two peptides: one from the third intracellular loop of the D2 dopamine receptor (D2N), and a second, Galpha.GDP-binding peptide (KB-752) that mimics the proposed role of Gbetagamma in receptor-promoted nucleotide exchange. The structure of both peptides in complex with Galpha(i1) suggests that conformational changes in the beta3/alpha2 loop and beta6 strand act in concert for efficient nucleotide exchange. Two key residues in the alpha4 helix were found to define a receptor/Galpha(i) coupling specificity determinant.
About this Structure
2HLB is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Structural basis for nucleotide exchange on G alpha i subunits and receptor coupling specificity., Johnston CA, Siderovski DP, Proc Natl Acad Sci U S A. 2007 Feb 6;104(6):2001-6. Epub 2007 Jan 30. PMID:17264214 Page seeded by OCA on Sun May 4 06:25:26 2008
