Interferon-γ induces receptor dimerization in solution and on cells

A. C. Greenlund, R. D. Schreiber, D. V. Goeddel, D. Pennica

Research output: Contribution to journalArticlepeer-review

83 Scopus citations

Abstract

The extracellular domain (ECD) of the human interferon-γ (IFNγ) receptor was stably expressed in Chinese hamster ovary cells and purified to homogeneity. Scatchard analysis of 125I-IFNγ binding to ECD preparations revealed the formation of a ligand-receptor complex which displayed a K(α) of 6.4 ± 0.9 x 108 M-1. Two types of complexes were identified by sucrose density gradient ultracentrifugation. The stoichiometry of the major ECD- ligand complex was determined by high performance liquid chromatography gel filtration. When IFNγ was incubated with a 2-fold molar excess of ECD, a 190-kDa complex was isolated that contained 2 mol of ECD per 1 mol of IFNγ. IFNγ also induced dimerization of IFNγ receptors expressed at the cell surface as detected by chemically cross-linking receptor bound ligand and analyzing cell lysates by SDS-polyacrylamide gel electrophoresis and immunoblotting. Finally, labeled forms of ECD bound to cells preincubated at 4 °C with excess amounts of IFNγ indicating that the ligand could associate with more than one receptor molecule in the absence of chemical cross- linking agents. These results demonstrate that IFNγ effects dimerization of its receptor under physiologic conditions and suggest that IFNγ receptor dimerization may be an important event in inducing IFNγ-dependent biologic responses.

Original languageEnglish
Pages (from-to)18103-18110
Number of pages8
JournalJournal of Biological Chemistry
Volume268
Issue number24
StatePublished - 1993

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