A 100-kilodalton protein is associated with the murine interleukin 2 receptor: biochemical evidence that p100 is distinct from the alpha and beta chains.
Two proteins that specifically bind the T-cell growth factor interleukin 2 (IL-2) have been identified previously on the surface of T cells; these proteins have been designated IL-2R alpha and IL-2R beta for the alpha and beta chains of the IL-2 receptor (IL-2R). The association of these independent binding proteins with each other on the surface of activated T cells correlates with the generation of high-affinity binding sites. These high-affinity sites transduce the major mitogenic signal of IL-2, yet the mechanisms of association of the alpha and beta chains with each other as well as signal transduction in response to IL-2 are unknown. Cotransfection experiments of cDNAs encoding the alpha and beta chains in T cells and fibroblasts have suggested functional requirements for other T cell-specific factor(s). We now provide biochemical evidence for a distinct 100-kDa protein that interacts with the alpha or beta chains, or both, on the surface of the IL-2-dependent cell line CTLL-2 as well as activated murine splenocytes. This same 100-kDa protein is capable of being chemically cross-linked to 125I-labeled IL-2.
Sharon
M
M
Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.
Gnarra
J R
JR
Leonard
W J
WJ
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology; D046911:Macromolecular Substances; D051379:Mice; D008970:Molecular Weight; D010449:Peptide Mapping; D015375:Receptors, Interleukin-2 / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D014162:Transfection
D046911:Macromolecular Substances; D015375:Receptors, Interleukin-2