Physicochemical properties of amino acid sequences of G-proteins for understanding GPCR-G-protein coupling

Abstract

A G-protein binds to a G-protein-coupled-receptor (GPCR) by physical interactions between the amino acid sequences. Various physical properties of possible binding regions at the C- and N-termini of α subunits of G-proteins were analyzed in order to classify the four families of α subunits, α _s, α _i/o, α _q/11 and α _12/13, as well as the eight subfamilies. The distribution of the charge density and the hydrophobicity of 100 residues at the C-terminus enabled discrimination of the four families of α subunits, whereas the same physical properties of 60 residues at the N-terminus enabled discrimination of the subfamilies.