INVITRO SYNTHESIS, GLYCOSYLATION, AND MEMBRANE INSERTION OF INFLUENZA-VIRUS HEMAGGLUTININ

The synthesis of influenza virus haemagglutinin (HA) has been studied, using cell-free systems primed with cellular RNA from chick embryo fibroblast (CEF) cells infected with influenza virus (A/Japan/305/57-Bellamy/42(H2N1)). In L-cell and wheat germ cell-free systems, a precursor to the HA protein of apparent molecular weight 63,000 was identified by immunoprecipitation and by comparative peptide mapping of this product and the 75,000-dalton glycopolypeptide HA precursor synthesised during infection of CEF cells. The 63,000-dalton precursor was converted to a product of apparent molecular weight 75,000 by addition of dog pancreas membrane vesicles during in vitro translation. The 75,000-dalton protein made in the presence of membranes is protected from trypsin digestion and binds to lectin-Sepharose. These, and further results, suggest that HA is extruded into membrane vesicles and glycosylated during synthesis. © 1979.