Disposition of T200 glycoprotein in the plasma membrane of a murine lymphoma cell line.
T200 glycoprotein, a major cell surface component of murine hematopoietic cells, is a phosphorylated transmembrane glycoprotein. Two distinct regions of the molecule can be defined by radiolabeling with a variety of metabolic precursors or by lactoperoxidase-catalyzed iodination, in combination with protease treatments, immunoprecipitation techniques, and peptide "mapping" analysis. A relative protease-resistant domain, which is exposed on the cell surface and contains the antigenic site recognized by a monoclonal anti-T200 antibody known to react with the exterior cell surface, contains most if not all of the mannose-containing oligosaccharide units of the glycoprotein and all of the amino acid residues labeled by lactoperoxidase-catalyzed iodination of intact viable cells. This protease-resistant fragment migrates with an apparent molecular weight of approximately 100,000 in sodium dodecyl sulfate-polyacrylamide gels. The remaining portion of the molecule contains a region, extensively digested by trypsin, which is exposed on the cytoplasmic side of the plasma membrane and contains phosphoserine residues which can be labeled with 32PO4 in vivo. A 125I-labeled tryptic peptide derived from this region of the molecule was obtained if membrane preparations from cells disrupted by nitrogen cavitation were labeled by lactoperoxidase-catalyzed iodination.
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis*; D007118:Immunoassay; D007700:Kinetics; D008223:Lymphoma; D008565:Membrane Proteins / Q000032:analysis*; D051379:Mice; D008970:Molecular Weight; D009363:Neoplasm Proteins / Q000032:analysis*; D010446:Peptide Fragments / Q000032:analysis; D014357:Trypsin / Q000378:metabolism
D006023:Glycoproteins; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D010446:Peptide Fragments; D014357:Trypsin