Structural polypeptide composition of a murine myeloma (MOPC-315) type C retrovirus

The polypeptide composition of an endogenous NB-tropic type C retrovirus of murine myeloma MOPC-315 cells was analyzed by agarose gel chromatography in 6 M guanidine hydrochloride and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Seven polypeptides were reproducibly resolved: five with estimated molecular weights of 110,000, 70,000, 45,000, 15,000 and 10,000 daltons, and two with molecular weights of 30,000 daltons. The 110,000-, 70,000- and 45,000-dalton polypeptides were found to be glycosylated, and of these the 70,000-dalton protein was the major glycoprotein, while the 45,000-dalton protein was minor and poorly glycosylated. The two 30,000-dalton polypeptides of MOPC-315 virus which were found to be identical with regard to their peptide profile share antigenic determinants with the Mo-MuLV-derived 30,000 protein but differ from it in their peptide composition. The findings of two 30,000-dalton proteins in an additional member of the myeloma viruses coupled with the presence of unusual high molecular weight glycoproteins, provides further evidence in support of the notion that the myeloma type C viruses comprise a distinct group within the murine leukemia viruses.