title: Glycoproteins of Sendai virus (HVJ) have a critical ratio for fusion between virus envelopes and cell membranes.
abstract: The biological activity of two glycoproteins, hemagglutinin and neuraminidase (HN) and fusion (F) proteins, of Sendai virus (HVJ) were studied using purified proteins. The proteins were purified by chromatography on DEAE and CM cellulose in the presence of Nonidet P-40 (NP40). The glycoproteins were reconstituted at various ratios of F to HN into lipid vesicles containing fragment A of diphtheria toxin. The association of HN and F proteins with the vesicles was confirmed by electron microscopy and sucrose density gradient centrifugation. The cytotoxic activity of vesicles containing fragment A on fusion with L cells was determined by measuring colony formation of the cells. It was found that for maximum cytotoxic activity of the vesicles, there was an optimal ratio of F to HN of two. This suggests that HN is not merely the initial binding site to the cell surface, and that interactions between HN and F proteins on the virus surface may be important for the biological activities of these proteins on the cells.
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D004167:Diphtheria Toxin / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006389:Hemagglutinins, Viral / Q000378:metabolism*; D008051:Lipid Bilayers / Q000378:metabolism; D051379:Mice; D009439:Neuraminidase / Q000378:metabolism*; D010222:Parainfluenza Virus 1, Human / Q000502:physiology*; D010446:Peptide Fragments / Q000378:metabolism; D014760:Viral Fusion Proteins; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D004167:Diphtheria Toxin; D006389:Hemagglutinins, Viral; D008051:Lipid Bilayers; D010446:Peptide Fragments; D014760:Viral Fusion Proteins; D014764:Viral Proteins; C029795:diphtheria toxin fragment A; D009439:Neuraminidase