The Structure and Biosynthesis of the Carbohydrate Moiety of the Influenza Virus Hemagglutinin
Analysis of glycopeptides obtained after digestion with Pronase indicates that the hemagglutinin has at least two different types of carbohydrate side chains. The side chain of type I is composed of glucosamine, mannose, galactose and fucose. It is found on HA 1 and HA 2. The corresponding glycopeptide has a molecular weight of 2,600 suggesting that there are about 12 monosaccharide units in the chain. The side chain of type II contains a high amount of mannose and is found exclusively on HA2. The corresponding glycopeptide has a molecular weight of 2,000 suggesting that there are about 9 monosaccharide units. The number of side chains per HA molecule appears to be in the range of 5 to 6. Host-specific variations in the carbohydrate content of the hemagglutinin are due to differences in size, not in number, of side chains.
Glycosylation of the hemagglutinin occurs in a stepwise manner. There is suggestive evidence that the core sugars (glucosamine and mannose) are synthesized in covalent linkage to polyisoprenol and transferred en bloc from the lipid to the polypeptide. This takes place at the rough endoplasmic reticulum. After migration of the hemagglutinin to the smooth endoplasmic reticulum, glycosylation is completed by the attachment of the peripheral sugars (galactose and fucose).
KeywordsRough Endoplasmic Reticulum Smooth Endoplasmic Reticulum Viral Glycoprotein MDBK Cell Monosaccharide Unit
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- NEVILLE, D. M. Jr. (1974) in `Proceedings of the International Workshop on Cell Surfaces and Malignancy’ Fogarty International Centre, Bethesda, Maryland, U.S.A.Google Scholar
- ROTT, R. and KLENK, H-D. (1977) in `Virus Infection and the Cell Surface’ Cell Surface Reviews, Vol. 2, ( G. Poste and G. L. Nicolson, Eds.) Elsevier, North-Holland.Google Scholar
- SCHWARZ, R. T., SCHMIDT, M. F. G., ANWER, U. and KLENK, H-D. (1977) J. Virol., in press.Google Scholar