Amino acid compositions and amino-terminal sequences of the structural proteins of a flavivirus, European Tick-Borne Encephalitis virus.

N-terminal amino acid sequences of the three structural proteins E, C, and M of the flavivirus Tick-Borne Encephalitis virus comprising 4, 17, and 4 amino acid residues, respectively, have been determined. Each of these proteins has a unique N-terminal sequence. Since none of the three proteins possesses an N-terminal methionine residue, none contains an unprocessed translation initiation sequence. The amino acid composition of the three proteins has also been analyzed. The C protein is rich in basic amino acids. It contains neither tyrosine nor cysteine. The M protein is rich in leucine and contains only single residues of methionine and phenylalanine. The amino acid composition indicates that the M protein has a molecular weight of at least 8000 Da which is somewhat higher than the value of 7500 Da estimated for the molecular weight of this protein by SDS-PAGE. Further conclusions that can be drawn from these analyses are discussed.