The Mumps Virus Fusion Protein mRNA Sequence and Homology among the Paramyxoviridae Proteins

Department of Virology, School of Medicine, Karolinska Institute, Stockholm S-105 21, Sweden The complete nucleotide sequence of the fusion protein (F) mRNA of the virulent SBL-1 strain of mumps virus has been determined by sequencing cDNA clones and mRNA and confirmed by partially sequencing the genomic RNA. The mRNA was 1721 nucleotides long excluding the poly(A) sequence and had one long open reading frame which encoded a protein of 538 amino acids with a calculated M r of 58791. The predicted amino acid sequence had a proteolytic cleavage/activation site, Arg Arg His Lys Arg, cleavage at which yields proteins F 2 and F 1 . The uncleaved protein contained three highly hydrophobic regions: (i) the amino-terminal signal peptide, (ii) the aminoterminal region of F 1 and (iii) the carboxy-terminal membrane anchorage domain. There were seven potential N -glycosylation sites, two in F 2 and five in F 1 . Comparison of the virulent strain F protein sequence with that of an avirulent strain of mumps virus showed a difference of 14 amino acids. Among paramyxoviruses, mumps virus fusion protein shows the highest degree of homology with the fusion proteins of simian virus 5 and Newcastle disease virus. Keywords: mumps virus, fusion protein, nucleotide sequence, sequence homology Present address: Biotechnology Research Institute, National Research Council of Canada, 6100 Avenue Royal Mount, Montreal, Quebec, Canada H4P 2R2. Received 5 October 1988; accepted 29 November 1988.