Polypeptides of Moloney sarcoma-leukemia virions: their resolution and incorporation into extracellular virions

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) using four different concentrations of acrylamide resolved 16 polypeptide and glycopeptide components of Moloney sarcoma-leukemia virions radiolabeled with amino acids and d-glucosamine. Virions labeled with one neutral (lecuine or tryptophan) and one basic (lysine) amino acid show a distinctive label incorporation ratio for polypeptides in clustered molecular weight groups. One low molecular weight polypeptide is lysine rich, but is not a true histone since it was found to contain tryptophan.Several distinctive patterns of incorporation of pulse labeled (³H]leucine) polypeptides into virions were observed. For most virion polypeptides the highest amount of pulse label recovered per unit time in extracellular virions was from early chase intervals (0–30, or 30–60 min). During subsequent chase intervals (60–120, or 120–180 min), the amounts of ³H counts in these specific labeled polypeptides recovered in extracellular virus per unit time decreased exponentially. Pulse labeled copies of one low molecular weight polypeptide (16,000) and the two major virion glycoproteins (73,000 and 75,000) appeared in supernatant virions during early chase intervals (0–30 min) at a low level then increased in amount of label recovered per unit time during chase intervals of 30–60, and 60–120 min. A third unique incorporation pattern was observed for one low molecular weight polypeptide (18,000). Pulse labeled copies of this polypeptide were not detectable in supernatant virus during the first 30 min of chase, but appeared in increasing amounts recovered per unit time during chase intervals of 30–60, and 60–120 min.