Photoaffinity labeling of an interferon-gamma receptor on the surface of cultured fibroblasts.

Highly purified native and recombinant 125I-interferon-gamma was acylated with the photoreactive cross-linking reagent, N-succinimidyl-6(4'-azido-2'-nitrophenylamino) hexanoate. Derivatized interferon covalently labeled a cell surface component with an aggregate Mr = 230,000 +/- 7,000 (n = 7). Photoaffinity labeling was judged to be specific for the IFN-gamma receptor as it did not occur in the absence of light or in the presence of excess unlabeled interferon-gamma.