Comparative analysis of the N-glycans of rat, mouse and human Thy-1. Site-specific oligosaccharide patterns of neural Thy-1, a member of the immunoglobulin superfamily.
Protein structure and tissue type are known to influence glycosylation of proteins. We have previously investigated the N-glycans at each of the three glycosylation sites of the cell surface glycoprotein Thy-1 when isolated from rat brain and thymocytes. Here we report a comparative analysis of the site-specific N-glycosylation patterns from rat (Asn 23, 74, 98), mouse (Asn 23, 75, 99) and human (Asn 23, 60, 100) neural Thy-1. Despite considerable differences in amino acid sequence, the results show a remarkable conservation of the pattern of N-glycans at corresponding sites between the three species, as judged by chromatographic comparisons and glycosidase susceptibility. This is particularly marked for sites at Asn 74/75 in rat/mouse and the equivalent site at 60 in human Thy-1, as well as for sites at Asn 98/99 and 100, respectively. The sites at Asn 23 in rat/mouse also contained almost identical glycosylation patterns, but at this site human Thy-1 showed significantly different glycosylation patterns. These site glycosylation patterns are discussed in relation to the likely accessibility of the oligosaccharides for processing. It is known that within a species, the glycosylation of Thy-1 is tissue specific; therefore, this degree of conservation of glycosylation of Thy-1 expressed in the same tissue in different species is all the more striking, given the known variation between species in the amino acid sequence of Thy-1. It is therefore proposed that neural cells have a particular requirement for specific surface carbohydrates and that the Thy-1 polypeptide serves as an appropriate carrier for these structures.
Williams
A F
AF
MRC Cellular Immunology Unit, Sir William Dunn School of Pathology, University of Oxford, UK.
Parekh
R B
RB
Wing
D R
DR
Willis
A C
AC
Barclay
A N
AN
Dalchau
R
R
Fabre
J W
JW
Dwek
R A
RA
Rademacher
T W
TW
D000595:Amino Acid Sequence; D000818:Animals; D000954:Antigens, Surface / Q000737:chemistry* / Q000145:classification; D001923:Brain Chemistry; D006020:Glycopeptides / Q000737:chemistry; D006031:Glycosylation; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000145:classification; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D019158:N-Acetylneuraminic Acid; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000145:classification; D009844:Oligosaccharides / Q000737:chemistry / Q000145:classification; D010446:Peptide Fragments / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry* / Q000145:classification; D011487:Protein Conformation; D051381:Rats; D012045:Regulatory Sequences, Nucleic Acid; D017386:Sequence Homology, Amino Acid; D012794:Sialic Acids / Q000737:chemistry; D018800:Thy-1 Antigens
D000954:Antigens, Surface; D006020:Glycopeptides; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D009844:Oligosaccharides; D010446:Peptide Fragments; D011134:Polysaccharides; D012794:Sialic Acids; D018800:Thy-1 Antigens; D019158:N-Acetylneuraminic Acid