Interferon-induced synthesis of a 63,000 dalton protein in mouse cells

Cultures of mouse JLSV5 cells (a cell line chronically infected with Rauscher murine leukemia virus) and of fresh uninfected NMRI mouse embryo fibroblasts were treated with interferon and labelled with ( 35S)-methionine. Newly synthesized proteins were then examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional electrophoresis of the cell lysates. In both cell types interferon treatment resulted in the synthesis of a radioactive 63,000 dalton protein, which was undetectable in a radioactive form in the control cells. The possibility is considered that this protein is a mediator of the biological activities of interferon on cells.