Purification of the fusion protein of Sendai virus: analysis of the NH2-terminal sequence generated during precursor activation.
The two glycoproteins of Sendai virus, the hemagglutinin-neuraminidase and the fusion protein (F), were separated and purified by affinity chromatography on a Lens culinaris lectin-Sepharose column. F was shown to consist of two disulfide-bonded glycopolypeptide chains, F1 and F2, of molecular weights 51,000 and 11,000, each of which contained 15% carbohydrate by weight. Amino-terminal sequence analysis showed that F2 was blocked and that the hydrophobic sequence NH2-Phe-Phe-Gly-Ala-Val-Ile-Gly-Ile-Ile-Ala-Leu-Gly-Pro-Ala-Thr- was at the amino terminus of F1. This sequence shows identity at six positions with the hydrophobic amino-terminal sequence of the smaller glycopolypeptide chain, HA2, of the hemagglutinin of influenza virus. Both F1 and HA2 are formed by proteolytic cleavage of precursor glycoproteins (Fo, Sendai virus; HAo, influenza virus). Since these cleavages confer infectivity upon both Sendai and influenza viruses and the ability to induce cell-to-cell fusion upon Sendai virus, the hydrophobic NH2-terminal sequences on F1 and HA2 may play a role in fusion of viral and host-cell membranes.
D000595:Amino Acid Sequence; D002459:Cell Fusion; D006020:Glycopeptides / Q000032:analysis; D006023:Glycoproteins / Q000302:isolation & purification*; D006389:Hemagglutinins, Viral / Q000032:analysis / Q000302:isolation & purification*; D009975:Orthomyxoviridae / Q000032:analysis; D010222:Parainfluenza Virus 1, Human / Q000032:analysis*; D011498:Protein Precursors; D014764:Viral Proteins / Q000032:analysis / Q000302:isolation & purification*
D006020:Glycopeptides; D006023:Glycoproteins; D006389:Hemagglutinins, Viral; D011498:Protein Precursors; D014764:Viral Proteins