Intracellular processing of measles virus fusion protein.
Intracellular processing of measles virus fusion (F) protein was studied by radiolabeling and immunoprecipitation with a monoclonal antibody against F protein. The cleavage of F protein into F1 and F2 subunits was complete after 5 hours of chase during which the growth of oligosaccharide chains on the F2 domain of F protein continued. The addition of terminal sialic acid conferred a strong negative charge on the F2 subunit. F protein expressed on the cell surface was removed by a fungal semi-alkaline protease, providing a method to follow the kinetics of its transport to the cell surface. The transport of the F protein was faster than that of the hemagglutinin (HA) protein. Uncleaved F protein, as well as cleaved subunits became digestible by the protease, indicating that a portion of the F protein reaches the cell surface uncleaved. The treatment of measles virus-infected cells with tunicamycin resulted in the synthesis of unglycosylated HA (65 kilodaltons, Kd) and F (48 Kd) proteins. Unglycosylated F protein was not cleaved into smaller subunits, nor was it transported to the cell surface. Unglycosylated HA protein likewise failed to reach the cell surface.
Sato
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TA
Department of Measles Virus, National Institute of Health, Tokyo, Japan.
Kohama
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Sugiura
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D000911:Antibodies, Monoclonal; D001692:Biological Transport; D006031:Glycosylation; D006389:Hemagglutinins, Viral / Q000378:metabolism; D007526:Isoelectric Point; D008459:Measles virus / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D014415:Tunicamycin / Q000494:pharmacology; D014760:Viral Fusion Proteins / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D006389:Hemagglutinins, Viral; D008562:Membrane Glycoproteins; D014760:Viral Fusion Proteins; D014415:Tunicamycin; D010447:Peptide Hydrolases