Expression of nm23/NDP kinase proteins on the cell surface.
We determined whether proteins encoded by the nm23/nucleoside diphosphate (NDP) kinase gene, a potential metastasis-suppressor gene, are expressed on the cell surface. Monoclonal antibodies (mAb) specific for nm23-H1 or H2 proteins were prepared using the corresponding fusion proteins with glutathione S-transferase (GST) as immunogens. mAb H1-229 was specifically reactive with nm23-H1 protein, whereas mAb H2-439 was specific for nm23-H2 protein in immunoprecipitation and immunoblotting. mAb H1-229 was reactive with most human hematopoietic and some non-hematopoietic cell lines in flow cytometry. On the other hand, mAb H2-439 was reactive with only a limited number of cell lines. Based upon the surface expression of nm23/NDP kinase, cells were classified as nm23-H1+H2-, nm23-H1+H2+ or nm23-H1-H2-. No cell lines with nm23-H1-H2+ were found among those examined. The specificity of flow cytometry analysis was confirmed in the murine myeloma line NS-1 transfected with either the nm23-H1 or H2 genes. Both mAbs were reactive only to NS-1 transfected with the corresponding nm23 genes. Immunoprecipitation and SDS-PAGE analysis identified 20.5- and 18-kDa proteins with mAb H1-229 or H2-439, respectively, in cellular extracts of 125I-surface labeled NS-1 transfected with the corresponding genes. The presence of nm23/NDP kinase on the cell surface indicates an extracellular role for these proteins in addition to their reported intracellular functions.
Department of Oncology, Nagasaki University School of Medicine, Japan.
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Furukawa
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Shiku
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001483:Base Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry*; D006801:Humans; D015151:Immunoblotting; D008565:Membrane Proteins / Q000032:analysis*; D051379:Mice; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins; D054778:NM23 Nucleoside Diphosphate Kinases; D009701:Nucleoside-Diphosphate Kinase / Q000032:analysis* / Q000276:immunology; D009842:Oligopeptides; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D011506:Proteins / Q000032:analysis* / Q000276:immunology; D014157:Transcription Factors; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D008565:Membrane Proteins; D054778:NM23 Nucleoside Diphosphate Kinases; D009842:Oligopeptides; D011506:Proteins; D014157:Transcription Factors; C047981:arginyl-glycyl-aspartic acid; C517938:NME1 protein, human; C517939:Nme1 protein, mouse; D009701:Nucleoside-Diphosphate Kinase; D020559:Monomeric GTP-Binding Proteins