Title : The
asparagine-linked oligosaccharides at individual glycosylation
sites in human
thyrotrophin
Abstract :
- The asparagine-linked carbohydrate structures at each of the three glycosylation sites of human thyrotrophin were investigated by 400 MHz 1H-NMR spectroscopy
- Highly purified, biologically active human thyrotrophin ( hTSH ) was dissociated into its subunits hTSH alpha (glycosylated at Asn 52 and Asn 78 ) and hTSH beta (glycosylated at Asn 23 )
- The alpha-subunit was further treated with trypsin which gave two glycopeptides that were subsequently separated by reverse-phase HPLC and identified by amino acid sequence analysis
- The oligosaccharides were liberated from hTSH alpha glycopeptides and from intact hTSH beta by hydrazinolysis, and were fractionated as alditols by anion-exchange and ion-suppression amine-adsorption HPLC preparatory to structural analysis
- The N-glycans present on hTSH were mainly diantennary complex-type structures with a common Man alpha 1-3 branch that terminated with 4-O-sulphated GalNAc
- The Man alpha 1-6 branch displayed structural heterogeneity in the terminal sequence , with chiefly alpha 2-3-sialylated Gal and/or 4-O-sulphated GalNAc
- The relative amounts of the two major complete diantennary oligosaccharides and their core fucosylation differed according to glycosylation site ; the sulphated/sialylated diantennary oligosaccharide was most abundant at the two sites on the alpha-subunit , whereas the disulphated, core-fucosylated oligosaccharide was more plentiful on the beta-subunit
- Some interesting structural features, not previously reported for the N-glycans of hTSH , included 3-O-sulphated galactose (SO4-3Gal) and peripheral fucose (Fuc alpha 1-3GlcNAc) in the Man alpha 1-6 branch of some diantennary structures; the former suggests the presence of a hitherto uncharacterized galactose-3-O-sulphotransferase in thyrotroph cells of the human anterior pituitary gland
Output (sent_index, trigger,
protein,
sugar,
site):
- 0. glycosylation, , -, -, sites
- 1. asparagine-linked, , -, The asparagine-linked carbohydrate structures, asparagine
- 1. glycosylation, , thyrotrophin, -, sites
- 2. glycosylated, , -, -, Asn 52 and Asn 78
- 2. glycosylated, , hTSH alpha, -, Asn 52 and Asn 78
- 2. glycosylated, , hTSH beta, -, Asn 23
- 2. glycosylated, , subunits, -, Asn 23
- 2. glycosylated, , subunits, -, Asn 52 and Asn 78
- 3. glycopeptides, , -, -, glycopeptides
- 4. glycopeptides, , -, -, glycopeptides
- 4. liberated, , hTSH beta, The oligosaccharides, glycopeptides
- 5. present, , hTSH, The N-glycans, -
- 5. present, , hTSH, diantennary complex-type structures, -
- 6. 2-3-sialylated, , -, chiefly alpha 2-3-sialylated Gal, -
- 7. glycosylation, , -, -, site
- 7. sulphated/sialylated, , -, the sulphated/sialylated diantennary oligosaccharide, -
- 8. hTSH, , hTSH, the N-glycans, -
Output(Part-Of) (sent_index,
protein,
site):
- 0. thyrotrophin, sites
- 1. thyrotrophin, sites
- 4. hTSH alpha, glycopeptides
*Output_Site_Fusion* (sent_index,
protein,
sugar,
site):
- 2. hTSH alpha, -, Asn 52 and Asn 78
- 2. hTSH beta, -, Asn 23
- 2. subunits, -, Asn 23
- 2. subunits, -, Asn 52 and Asn 78