Structural and Partial Amino Acid Sequence Analysis of the Human Hemopoietic Progenitor Cell Antigen CD34

摘要: Monoclonal antibodies of the CD34 class all recognize a monomeric cell surface antigen approximately Mr 110,000 which is selectively expressed on human hemopoietic progenitor cells. This structure can be readily surface-labeled with [125I]actoperoxidase and by periodate-[3H]borohydride, but it labels only weakly [35S]methionine, [35Sl]cysteine, 3H-amino acids, or 3H-mannose, even after prolonged labeling periods. However, more efficiently labeled [3H]glucosamine. Lectin binding studies, sensitivity to certain glycosidases, gel filtration analysis glycans released alkaline hydrolysis indicate that this glycoprotein contains several complex-type N-linked as well highly sialylated O-linked glycans. Western blotting experiments show various fail detect desialylated and/or de-N-glycosylated forms antigen. Experiments involving use tunicamycin, together metabolic strongly suggest "turns over" very slowly in vivo. The not detectably 32P-phosphate vivo, nor are immune complexes containing associated phosphokinase activity vitro. Sequential immunoprecipitation studies member leukosialin/sialophorin family despite fact these molecules share structural similarities. Partial amino acid purified revealed no significant sequence similarity any previously described structures.