Interleukin-2 induces N-glycosylation in T-cells: characterization of human lymphocyte oligosaccharyltransferase.
We have investigated the enzyme mediating N-glycosylation in "resting" and activated lymphocytes. Normal peripheral blood lymphocytes (PBLs) were found to have low activity for glycosylation of a synthetic glycan acceptor peptide. N-glycosylation activity increased 10-fold after mitogen activation of PBLs. N-glycosylation activity remained elevated during long-term culture and expansion of human lymphocytes when growth was supported by interleukin-2. To our knowledge, this is the first biochemical evidence for induction of endoplasmic reticulum functions during T-cell activation. The enzyme mediating N-glycosylation in lymphocytes was localized predominantly but not entirely to a microsomal organelle by subcellular fractionation. After solubilization and 85-fold purification from salt-washed microsomes, the enzyme preparation contained four predominant proteins. N-terminal sequence analysis identified the proteins as ribophorin I, ribophorin II (doublet), and a 50-kDa homologue of Wbp1, a yeast protein essential for N-glycosylation.
Kumar
V
V
Department of Biochemistry, University of Connecticut Health Center, Farmington, Connecticut, 06030, USA. Vijay_Kumar@dfci.harvard.edu
Heinemann
F S
FS
Ozols
J
J
D000595:Amino Acid Sequence; D006031:Glycosylation; D006602:Hexosyltransferases; D006801:Humans; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000494:pharmacology*; D008213:Lymphocyte Activation; D008565:Membrane Proteins; D008861:Microsomes / Q000201:enzymology; D008969:Molecular Sequence Data; D013601:T-Lymphocytes / Q000187:drug effects* / Q000201:enzymology* / Q000276:immunology; D014166:Transferases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D007376:Interleukin-2; D008565:Membrane Proteins; D014166:Transferases; D006602:Hexosyltransferases; C025620:dolichyl-diphosphooligosaccharide - protein glycotransferase