Characterization of the MHV-JHM Non-Structural Protein Encoded by mRNA 2
The genome of the murine Coronavirus MHV-JHM is a positive-stranded RNA of approximately 30 Kb, which encodes 4 structural proteins (N, M, S and HE) and at least 4 non-structural proteins. The location of the major open reading frames (ORFs) in the genome is shown in Fig. 1. In the infected cell, expression of the viral proteins is mediated by a set of subgenomic mRNAs. In relation to the genome the mRNAs are 3′ coterminal and extend to different positions in a 5′ direction. The mRNAs 7, 6, 3 and 2-1 have been shown to encode the N, M, S and HE proteins respectively (Siddell, 1983; Pfleiderer et al., this volume). mRNA 4 encodes a 15,000 molecular weight (mol.wt.) non-structural protein (Ebner et al, 1988) and mRNA 5 has the potential to encode two non-structural proteins of 12,400 and 10,200 mol.wt. (Skinner et al., 1985). Earlier in vitro translation studies (Siddell, 1983), indicated that the MHV-JHM subgenomic mRNA 2 encodes a 30,000 mol.wt. nonstructural protein, the expression of which was translationally regulated. Recent sequence analysis of the 5′ proximal region of the closely related MHV-A5 9 mRNA 2 confirms the presence of a 261 aminoacid ORF at this position. Analysis of the predicted polypeptide sequence indicates a non-membrane protein which may possibly have nucleotide binding and phosphorylating properties (Luytjes et al., 1988).
KeywordsFusion Protein Nonstructural Protein Rabbit Reticulocyte Lysate Infected Cell Lysate Positive Immune Reaction
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