Experiments were undertaken to test the hypothesis that the p24/CD9 cell surface molecule (originally detected on acute lymphoblastic leukemia cells) and the p21 protein encoded by the ras gene family are related. Immunoprecipitation and guanine nucleotide binding assays conducted with BA-2 and anti-p21/ras monoclonal antibodies showed no evidence that p24/CD9 is structurally or functionally related to p21/ras.
Bibliographical noteFunding Information:
THE PRODUCTION and characterization of monoclonal antibodies recognizing cell surface molecules expressed on human lymphohematopoietic cells has been undertaken by numerous laboratories. Several years ago we produced a monoclonal antibody (designated BA-2) against human acute lymphoblastic leukemia (ALL) cells that recognizes a 24-kilodalton (kDa) cell surface molecule \[13\].E xtensive structural studies have revealed that p24 is a non-integral membrane molecule that does not contain detectable N-linked oligosaccharides, does contain covalently attached fatty acid, and is non-covalently associated with a homologous molecule designated p26 \[17, 19\]. Subsequent to our initial study \[13\], we and others reported that BA-2 and additional anti-p24 monoclonal antibodies are broadly reactive with normal and malignant lymphohematopoietic and nonlympbohematopoietic cells \[2, 3, 5, 9, 10, 12, 14, 21\]. The p24 molecule (hereafter referred to as *This work was supported by CA-21737, CA-25097, CA-31685 and RR-05385 from the National Institutes of Health, and the Leukemia Research Fund (formerly the Leukemia Task Force). T.W.L. is a Scholar of the Leukemia Society of America. .4bhreviations: ALL, acute lymphoblastic leukemia; kDa, kilodahon; HaMuSI/; Harvey routine sarcoma virus; KiMuSV, Kirsten murine sarcoma virus; RIP, radioimmunoprecipita-tion: SDS-PAGE, sodium dodecyt sulfate-polyacrylamide gel clectrophoresis; GTP, guanosine triphosphate.
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- guanine nucleotide binding