| Abstract
| - The functional Interleukin 2 receptor (IL-2R) consists of at least two IL-2 binding cell surface molecules, IL-2Rα and IL-2Rβ, the latter component being responsible for the Intracellular growth signal transduction. In this study we attempted to identify the critical amino acid residues in the cytoplasmic domain of human IL-2Rβ for such signal transduction by expressing mutated IL-2Rβ cDNAs in a pro-B cell line, BAF-B03. We demonstrate that a singla amino acidsubstitution within the ‘serine-rich’ cytoplasmic region of IL-2Rβ (i.e. Leu299 changed to Pro) completely abrogates the receptor function in growth stimulation, but not in ligand binding. We also show that the murine erythropoletin receptor (EPO-R) is functional in BAF-B03, but that chimeric receptors, essentially possessing the IL-2Rβ extracellular and a homologous region derived from EPO-R cytoplasmic domain, are not capable of transducing the IL-2- inducedsignal.
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