Fusion glycoprotein of measles virus: nucleotide sequence of the gene and comparison with other paramyxoviruses.

The sequence of the fusion (F) glycoprotein mRNA of the Hallé strain of measles virus was determined from a cDNA clone representing the entire length of the mRNA. It contained 2384 nucleotides, excluding poly(A), with a 5' consensus sequence typical of paramyxoviruses and a 3' terminus found in measles virus mRNAs. The coding sequence was preceded by an unusually long (580 nucleotide) 5' non-translated region, which contained 44% cytosine. The longest open reading frame coded for a polypeptide of 553 amino acids with a predicted molecular weight of 59.84 K. Comparison of the sequence with that of the Edmonston strain of measles virus showed that the gene is highly conserved. No amino acid differences were observed between the two strains. The F polypeptide had three regions of high hydrophobicity: an N-terminal signal peptide, the N-terminus of F1 and a C-terminal membrane-spanning region. The four potential asparagine-linked glycosylation sites (one in the signal peptide) were all in the F2 subunit. Comparison of the measles virus F amino acid sequence with other paramyxoviruses revealed homologies with these viruses. Certain regions such as the N terminus of F1 and ten cysteine residues which probably impose structural restraints were highly conserved.