Title : Characterization and dynamics of O-linked glycosylation of human
cytokeratin 8 and 18
Abstract :
- The glycosylation of human cytokeratin ( CK) 8 and 18 was studied after metabolic labeling of HT29 colonic cells with [3H]glucosamine
- Labeling of CK8 /18 was not inhibited by tunicamycin, suggesting that glycosylation was not N-linked
- Acid hydrolysis of CK8 and CK18 , purified from [3H]glucosamine-labeled cells, generated free glucosamine
- In the presence of UDP-[3H]galactose, galactosyltransferase catalyzed the labeling of cytokeratin 8 and 18
- beta-Elimination of the [3H]galactose- labeled CK8/18 generated the disaccharide N-acetyllactosaminitol, indicating that cytokeratin 8 and 18 contain single O-linked N-acetylglucosamine residues
- Using chemical analysis, the stoichiometry of glycosylation was found to be 1.5 and 2 molecules of N-acetylglucosamine/protein molecule of CK8 and CK18 , respectively
- Peptide maps of [3H]glucosamine-labeled CK8/18 showed that multiple peptides were labeled with the amino sugar
- The biosynthetic and degradation rates of the carbohydrate moiety were faster than the protein core as determined by metabolic radiolabeling or pulse-chase experiments, respectively
- Our results show that CK8 and 18 are glycosylated at multiple sites with a single O-linked N-acetylglucosamine
- Furthermore, CK8 /18 glycosylation is a dynamic process which is likely to have functional relevance
Output (sent_index, trigger,
protein,
sugar,
site):
- 0. glycosylation, , cytokeratin 8, -, -
- 1. glycosylation, , CK) 8, -, -
- 1. glycosylation, , cytokeratin, -, -
- 5. contain, , cytokeratin 8, single O-linked N-acetylglucosamine residues, -
- 6. CK18, , CK18, N-acetylglucosamine/protein molecule, -
- 6. CK8, , CK8, N-acetylglucosamine/protein molecule, -
- 9. glycosylated, , CK8, -, sites
- 9. sites, , -, a single O-linked N-acetylglucosamine, sites
Output(Part-Of) (sent_index,
protein,
site):
*Output_Site_Fusion* (sent_index,
protein,
sugar,
site):