TAPA-1, the target of an antiproliferative antibody, is associated on the cell surface with the Leu-13 antigen.
A murine mAb, 5A6 (IgG1), has been isolated by immunization with a human B lymphoma cell line and screening for growth inhibition. The antibody immunoprecipitated a single chain protein of 26 kDa from cell lysates made with Triton X-100 but additional proteins were precipitated when cell lysates were made with the milder detergent CHAPS (3-[3-cholamidopropyl)dimethylammonio)-1-propane sulfate). We have identified one of these coprecipitated molecules as the 16-kDa Leu-13 Ag. 5A6 and anti-Leu-13 showed similar, although not identical, reactivity, growth inhibition and temperature-dependent aggregation effects among hematolymphoid cell lines. The aggregation induced by 5A6 and anti-Leu-13 was not dependent on LFA-1 (lymphocyte function-associated Ag-1). The cell-surface expression of both TAPA-1 (target of an antiproliferative antibody-1) and Leu-13 could be down-modulated by binding to their respective antibodies and they could be reciprocally comodulated. These results suggest that TAPA-1 and Leu-13 form a complex on the cell surface and play a role in growth control through a common pathway.
Department of Medicine/Oncology, Stanford University Medical Center, CA 94305.
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Takahashi
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Levy
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D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000502:physiology*; D000954:Antigens, Surface / Q000502:physiology*; D002449:Cell Aggregation; D002455:Cell Division; D004705:Endocytosis; D006801:Humans; D008214:Lymphocytes / Q000276:immunology*; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000502:physiology*; D011233:Precipitin Tests; D011940:Receptor Aggregation; D015398:Signal Transduction; D013696:Temperature; D060225:Tetraspanin 28
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D000954:Antigens, Surface; C554798:CD81 protein, human; D046911:Macromolecular Substances; D008565:Membrane Proteins; D060225:Tetraspanin 28; C062010:leu-13 antigen