title: Further characterization of mouse hepatitis virus RNA-dependent RNA polymerases.
abstract: Two temporally and enzymatically distinct RNA-dependent RNA polymerase activities associated with membranes of the mouse hepatitis virus (MHV)-infected cells have been identified previously [Brayton et al., J. Virol. 42, 847-853 (1982)]. In this paper, the subcellular distribution and functions of these two polymerases were examined. Fractionation of the postnuclear membranes by sucrose gradient sedimentation showed that the early polymerase activity (detected at 1 hr p.i.) was homogeneous, while the late polymerase (6 hr p.i.) was associated with two distinct membrane fractions. The early polymerase synthesized a single RNA species of viral genomic size and negative sense. In contrast, the light peak of the late polymerase synthesized genomic-sized RNA of positive sense, while the heavy peak of the activity synthesized positive-sensed genomic and subgenomic mRNAs. These findings suggest that the light peak of the late polymerase represents a replication complex while the heavy peak represents a transcription complex. They also establish the essential features of the mode of replication of MHV.
mesh_terms: D000818:Animals; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D008970:Molecular Weight; D006517:Murine hepatitis virus / Q000201:enzymology* / Q000235:genetics; D009685:Nuclear Envelope / Q000201:enzymology; D009693:Nucleic Acid Hybridization; D012316:RNA Nucleotidyltransferases / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics / Q000302:isolation & purification; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger; D012367:RNA, Viral; D004247:DNA; D012316:RNA Nucleotidyltransferases; D012324:RNA-Dependent RNA Polymerase