| 2147181 |
Fountoulakis M, Juranville JF, Maris A, Ozmen L, Garotta G: One interferon gamma receptor binds one interferon gamma dimer. . J Biol Chem. 1990 Nov 15;265(32):19758-67.
We investigated the stoichiometry of the interferon gamma and interferon gamma receptor interaction, using recombinant interferon gamma and recombinant soluble interferon gamma receptor, applying chemical cross-linking and chromatographic techniques, and analyzing the resulting products in denaturing polyacrylamide gels. Interferon gamma cross-linked to itself produced a major band of an apparent molecular mass of 34 kDa, which suggests that it exists as a dimer in physiological buffer and which agrees with published data. Soluble interferon gamma receptor cross-linked to itself produced mainly a 28-kDa band, suggesting that the interferon gamma receptor exists as a monomer. Interferon gamma cross-linked to the soluble interferon gamma receptor resulted in the formation of two main products of apparent molecular masses of 60 and 44 kDa. The predominant 60-kDa band resulted from the cross-linking of one interferon gamma dimer (34 kDa) to one interferon gamma receptor molecule (27 kDa). The 44-kDa band was formed by the cross-linking of one interferon gamma molecule to one interferon gamma receptor. Kinetic studies showed that the cross-linking of interferon gamma dimer to the soluble receptor proceeds through the intermediate formed by cross-linking one molecule of the interferon gamma dimer to the receptor. Reducing and dissociating agents inhibited complex formation. When chromatographed on Sephadex G-100, interferon gamma was eluted as a protein of 34-kDa molecular mass, the soluble interferon gamma receptor as a protein of 40 kDa, and their mixture was eluted in one peak corresponding to an apparent molecular mass of 73 kDa. Sodium dodecyl sulfate-polyacrylamide gel analysis of the eluted mixture showed the presence of both interferon gamma and interferon gamma receptor at a ratio of 2:1. The found results suggest that the interferon gamma receptor binds interferon gamma as a dimer. |
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