Identification of a receptor for peptides of the bombesin family in Swiss 3T3 cells by affinity cross-linking.

The cross-linking agent ethylene glycol-bis(succinimidyl succinate) was used to covalently link 125I-labeled gastrin releasing peptide (125I-GRP) to an Mr 75,000-85,000 surface protein in Swiss 3T3 cells that displays many characteristics of a specific receptor for peptides of the bombesin family. This protein was not present in other cell lines which do not exhibit receptors for bombesin-like peptides. Unlabeled GRP competed for affinity labeling of the Mr 75,000-85,000 protein in a concentration-dependent manner, and other bombesin-related peptides also inhibited the cross-linking of 125I-GRP to this component. In contrast, high concentrations of a variety of other peptide hormones and mitogens had no effect. Affinity labeling of the Mr 75,000-85,000 protein was dependent on the concentration of 125I-GRP and exhibited saturability. 125I-GRP affinity labeling of this protein was also demonstrated by two-dimensional gel electrophoresis. These studies suggest that an Mr 75,000-85,000 surface protein with an isoelectric point of 6.0 to 6.5 is a major component of the receptor for peptides of the bombesin family in Swiss 3T3 cells.