Biochemical characterisation of leukaemia-associated antigen p24 defined by the monoclonal antibody BA-2.
The leukaemia-associated cell surface antigen p24/BA-2 is a single polypeptide chain with a molecular weight of 24,000. Treatment with glycosidases or exposure of cells to tunicamycin failed to show any change in the molecular weight of the antigen when examined by SDS-polyacrylamide gel electrophoresis. In addition, it failed to bind to lectin affinity columns of concanavalin A, lentil lectin or ricinus communis lectin. This is consistent with the absence of N-asparagine linked oligosaccharide chains on the antigen. Pulse-chase labelling of protein p24 shows a post-translational modification resulting in a molecular weight increase of approx. 500-1000. Alkaline treatment resulted in a decrease in molecular weight of approximately the same amount, suggesting that p24 contain some O-glycosidically linked oligosaccharide. Protein p24 has a basic pI of 7.3 which is unchanged after neuraminidase treatment. Protein P24/Ba-2 cannot be labelled by either the lipophilic photoactivatable nitrene reagent, hexanoyldiiodo-N-(4-azido-2-nitrophenyl)tyramine, or with [32P]phosphate. This suggests that the molecule is non-integral in nature and that it does not form an intimate association with the lipid matrix. Identical molecular weights, when reduced and non-reduced antigens were compared, suggest that it contains no internal disulphide linkages and failure to detect any other band on gradient gel SDS-polyacrylamide gel electrophoresis from 5-15% suggests that is is not strongly associated with any other structure.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000951:Antigens, Neoplasm / Q000276:immunology*; D001854:Bone Marrow Cells; D002460:Cell Line; D055598:Chemical Phenomena; D002621:Chemistry; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D007945:Leukemia, Lymphoid / Q000276:immunology*; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008970:Molecular Weight; D009844:Oligosaccharides
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D009844:Oligosaccharides