A core polyprotein of murine leukemia virus on the surface of mouse leukemia cells.

A polypeptide of molecular weight approximately 75,000 daltons, p(75), was identified on the surface of AKR spontaneous leukemia cells by lactoperoxidase-catalyzed radio-iodination. This protein was shown by immunoprecipitation to have antigenic determinants of MuLV p30, p15, and p10, but not gp70, suggesting that p(75) represents a polyprotein composed of virion core components. As evidenced by studies on incorporation of radioactive glucosamine, p(75) is probably glycosylated. No p(75) was found on 2 month old AKR thymocytes, and only a small amount of p(75) was detectable of thymocytes from 4 month old animals. However, substantial quantities of p(75) could be found on thymocytes from 6 month old, yet still preleukemic mice.