NMR structure of a receptor-bound G-protein peptide

Nature 363, 276–280 (1993)

In this Letter we reversed the assignment of the amino proton resonances of 8HN (Cys 347) and 11HN (Phe 350), as pointed out by J. Russo and L. M. Gierasch (personal communication). This correction caused some alterations in the preferred structures at the same level of refinement as used in our Letter; however, further refinement has led to additional alterations in the receptor-bound structures. Some of the peptide-transferred NOESY NMR intensities showed evidence for mediation by rhodopsin protons at higher levels of structure refinement, as supported by spin-echo filtering of the rhodopsin magnetization during the Tr-NOESY mixing time. Protons on the large protein that are in intimate contact with the ligand can mediate ligand proton cross-relaxation and distort the apparent distances between ligand protons. Partial compensation for rhodopsin mediation of peptide Tr-NOESY, by spin-echo filtering, led to further alterations of the structures and considerable improvement of the agreement of the bound peptide structures with the data¹. More quantitative estimation of receptor mediation of peptide Tr-NOESY and refined structures of receptor-bound G-protein peptides will be published later.