Analysis of murine interferon-γ binding to its receptor on intact cells and solubilized membranes Identification of an 80 kDa receptor

Abstract The receptor for murine-interferon-γ (Mu-IFN-γ) has been characterized for its molecular size and equilibrium binding constant on a thymoma cell line, EL-4. Binding of 125 I-IFN-γ to intact cells and their solubilized membranes has shown a single class of receptor with K d values of 1.9 × 10 −9 M and 1.3 × 10 −8 M, respectively. It was shown that solubilization of the Mu-IFN-γ receptor with a Zwitterionic detergent (Chaps) preserves its binding activity. A direct comparison of the molecular mass of the Mu-IFN-γ receptor on intact cells versus detergent-solubilized membranes was performed using a radiolabeled photoactivated crosslinking reagent and direct hybridization with 125 I-labeled IFN-γ on Western blots of solubilized receptor. The results indicate that both types of receptors have an identical molecular mass of ∼80 kDa.