Article Abstract:
Analysis of the symmetrical structure of viral spike glycoprotein complexes in animal viruses revealed new features about their role during membrane fusion during virus entry. The major glycoproteins responsible for protein activation in flaviviruses and alphaviruses were examined. In flaviviruses, glycoprotein M formed by proteolytic cleavage activates glycoprotein E which is responsible for membrane fusion. In alphaviruses, the glycopolypeptides E1 and E2 are synthesized in the endoplasmic reticulum (ER). E1 joins with p62, a precursor of E2, to form the heterocomplex outside the ER.
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Article Abstract:
The binding of ribonuclease B (RNase B) Man7-Man9 glycoforms to the luminal domain of calnexin is investigated in vitro. RNase B is assumed to be monoglucosylated. The binding process is a separate event from glycoprotein conformation and calnexin protects the ribonuclease from the action of glucosidase II and PNGase F but not from Endo H, which releases the protein from calnexin. Such data directly show that calnexin is capable of exclusively functioning as a lectin.
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Article Abstract:
An analysis of association between hemagglutinin and microsomal calnexin and its glucose-trimmed forms suggests that trimming and reglucosylation are important determinants of calnexin association in endoplasmic reticulum. The results also provide a mechanism for retaining unfolded and misfolded glycoproteins in ER and show that folding and glycosylation have a direct correlation.
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