Coding sequence of coronavirus MHV-JHM mRNA 4.

A coding sequence at the 5' end of mRNA 4 of the coronavirus MHV-JHM was determined by M13/chain-terminator sequencing of cloned cDNA. An open reading frame of 417 bases with the potential to encode a polypeptide of mol. wt. 15 200 (139 residues) was identified. The 3' end of the open reading frame overlapped by 16 bases the start of an open reading frame found in mRNA 5. The translation product of mRNA 4 was predicted to be a basic polypeptide rich in threonine. It had a large hydrophobic region near the amino terminus and a basic carboxy terminus. An intracellular, virus-specific polypeptide, which has been previously described having a mol. wt. of 14 000 to 14 500 has the size and charge characteristics of such a translation product.