Characterization of receptors for immune interferon in U937 cells with 32P-labeled human recombinant immune interferon.

Recombinant human immune interferon (HuIFN-gamma) was labeled with [gamma-32P]ATP and cyclic-AMP-dependent protein kinase from bovine heart to a specific radioactivity of 11,000 Ci/mmol. At least two molecules of phosphate were incorporated per molecule of interferon. The binding of [32P]HuIFN-gamma to human U937 histiocytic lymphoma cells was time dependent, and displaceable by HuIFN-gamma but not by HuIFN-alpha A or HuIFN-beta. The specific...