Isolation and characterization of a Mo-MuSV-transformed TB cell line that produces noninfectious MuSV particles with uncleaved gag protein which is processed in the presence of Mo-MuLV.
A cell line, TBSV7, that produces noninfectious murine sarcoma virus (MuSV) in the absence of helper MuLV was isolated from TB cells infected with the supernatant of MuSV349 cells. These noninfectious MuSV particles with "immature" C-type virus morphology contain a 2.2 X 10(6)-Da genomic RNA and an uncleaved 62,000-Da gag precursor protein (Pr62). Neither viral envelope proteins (gp70, p15E, p12E) nor reverse transcriptase were detected in these virus particles. Pr62 was found to be phosphorylated in vivo and it could be phosphorylated in vitro with [gamma-32P]ATP, indicating that protein kinase was packaged in these noninfectious virions. In vitro processing of Pr62 to smaller molecular weight proteins could be achieved by the addition of Mo-MuLV and Nonidet P-40. The initial cleavage products were proteins with molecular weights of 38K (Pr38) and 27K (Pr27). Under optimum conditions Pr38 was cleaved to p30 and a protein band migrating with MuLV-p10, while Pr27 was cleaved to a 17,000-Da protein that migrated slower than MuLV-p15 and a protein band migrating with MuLV-p12. Pulse-chase experiments performed on TBSV7 cells superinfected with Mo-MuLV indicated that intracellular processing of Pr62 was much slower than that of Pr65. Cleavage protein products of Pr62 similar in size to the in vitro protein products were also detected in TBSV7 cells superinfected with MuLV.
D000818:Animals; D002460:Cell Line; D002469:Cell Separation; D002472:Cell Transformation, Viral; D015683:Gene Products, gag; D051379:Mice; D008979:Moloney murine leukemia virus / Q000378:metabolism*; D010766:Phosphorylation; D011498:Protein Precursors / Q000032:analysis; D009053:Sarcoma Viruses, Murine / Q000302:isolation & purification*; D014764:Viral Proteins / Q000378:metabolism*; D014771:Virion / Q000302:isolation & purification*
D015683:Gene Products, gag; D011498:Protein Precursors; D014764:Viral Proteins