Biosynthesis of reovirus-specified polypeptides. Molecular cDNA cloning and nucleotide sequence of the reovirus serotype 1 Lang strain s4 mRNA which encodes the major capsid surface polypeptide sigma 3.

Serotype 1 Lang strain s4 mRNA, which encodes the major capsid surface polypeptide sigma 3 of reovirions, was cloned as a cDNA:mRNA heteroduplex in Escherichia coli using phage M13. A complete consensus nucleotide sequence for s4 mRNA has been determined from cDNA clones. The Lang strain s4 mRNA is 1196 nucleotides in length and possesses an open reading frame with a coding capacity of 365 amino acids, sufficient to account for a sigma 3 polypeptide of 41,212 daltons. Comparison of the serotype 1 (Lang) s4 sequence with the serotype 3 (Dearing) s4 sequence reveals 94% homology at the nucleotide level; the predicted sigma 3 polypeptides of the Lang and Dearing strains display 96% homology at the amino acid level. Two third base C codons (leu:CUC and ser:AGC) are used about one-tenth as frequently in the reovirus s4 mRNAs as compared to mammalian cellular mRNAs.