Biosynthesis of mouse Thy-1 antigen.
The biosynthesis and the maturation of Thy-1 antigen of mouse thymocytes have been studied by using a xenogeneic rabbit anti-mouse Thy-1 antibody. The earliest form of Thy-1 detected after a 5-min pulse with [35S]methionine and [35S]cysteine had an apparent m.w. of 26,500. During chase, this band converted to a molecular ratio (Mr) = 25,000 polypeptide, probably derived from the latter by trimming of glucose or mannose residues from the three high-mannose glycan units of Thy-1. Mature Thy-1 molecules were detected at the cell surface after a 15-min chase. At least one of the three N-linked oligosaccharide units was shown to be in the high mannose form at the cell surface, as indicated by its susceptibility to endo-beta-N-acetylglucosaminidase H digestion. Treatment of the early and late forms of Thy-1 antigen with endo-beta-N-acetylglucosaminidase F generated a single polypeptide of Mr = 13,500. The same precursor was obtained when cells were labeled in the presence of tunicamycin. This indicates the absence of O-linked glycan in the mature cell surface antigen. Finally, the resistance of Thy-1 antigen to trypsin digestion when associated with membranes confirmed that this molecule has no cytoplasmically oriented portion.
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D000818:Animals; D000937:Antigen-Antibody Reactions; D000954:Antigens, Surface / Q000032:analysis* / Q000302:isolation & purification; D008565:Membrane Proteins / Q000032:analysis; D051379:Mice; D008810:Mice, Inbred C57BL / Q000276:immunology*; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis; D011233:Precipitin Tests; D011498:Protein Precursors / Q000032:analysis; D013601:T-Lymphocytes / Q000378:metabolism*; D018800:Thy-1 Antigens
D000954:Antigens, Surface; D008565:Membrane Proteins; D010455:Peptides; D011498:Protein Precursors; D018800:Thy-1 Antigens