biostudies-literaturePearse BRNCI NIH HHSNIGMS NIH HHS309-20https://www.ebi.ac.uk/biostudies/studies/S-EPMC2315677biostudies-literatureUnknown181(2)The endoplasmic reticulum (ER) protein GT1 (UDP-glucose: glycoprotein glucosyltransferase) is the central enzyme that modifies N-linked carbohydrates based upon the properties of the polypeptide backbone of the maturing substrate. GT1 adds glucose residues to nonglucosylated proteins that fail the quality control test, supporting ER retention through persistent binding to the lectin chaperones calnexin and calreticulin. How GT1 functions in its native environment on a maturing substrate is poorly understood. We analyzed the reglucosylation of a maturing model glycoprotein, influenza hemagglutinin (HA), in the intact mammalian ER. GT1 reglucosylated N-linked glycans in the slow-folding stem domain of HA once the nascent chain was released from the ribosome. Maturation mutants that disruptedThe Journal of cell biologyA cell-based reglucosylation assay demonstrates the role of GT1 in the quality control of a maturing glycoprotein.PMC2315677T32GM00815CA79864R01 CA079864T32 GM008515Wang NHebert DNPearse BRGabriel LfalseA cell-based reglucosylation assay demonstrates the role of GT1 in the quality control of a maturing glycoprotein.The endoplasmic reticulum (ER) protein GT1 (UDP-glucose: glycoprotein glucosyltransferase) is the central enzyme that modifies N-linked carbohydrates based upon the properties of the polypeptide backbone of the maturing substrate. GT1 adds glucose residues to nonglucosylated proteins that fail the quality control test, supporting ER retention through persistent binding to the lectin chaperones calnexin and calreticulin. How GT1 functions in its native environment on a maturing substrate is poorly understood. We analyzed the reglucosylation of a maturing model glycoprotein, influenza hemagglutinin (HA), in the intact mammalian ER. GT1 reglucosylated N-linked glycans in the slow-folding stem domain of HA once the nascent chain was released from the ribosome. Maturation mutants that disrupted2008-01-01T00:00:00Z2008 Apr2025-04-22T07:04:50.774Z2019-03-26T23:19:59ZS-EPMC23156771842697810.1083/jcb.200712068