Direct identification of the murine IL-2 receptor p55-p75 heterodimer in the absence of IL-2.
The proteins cross-linked to the IL-2R p55 subunit were biochemically compared in distinct cell populations that varied in their capacity to express high affinity IL-2R. We directly cross-linked p75 to p55 in the absence of IL-2 for the cell populations that bear only high affinity IL-2R. Furthermore, although no endogenous IL-2 production was detected, p75 was readily cross-linked to p55 for EL4J-3.4, a p55 transfectant of EL4 that bears high affinity IL-2R. These results strongly suggest that high affinity IL-2R exist as a preformed heterodimer of p55 and p75 which do not require IL-2 for their association. Furthermore, cross-linking of three other proteins of apparent Mr of 100,000, 135,000, and 180,000 to p55 was also seen, raising the possibility of a more complex subunit composition for the IL-2R.
D000818:Animals; D002460:Cell Line; D003432:Cross-Linking Reagents; D007376:Interleukin-2 / Q000378:metabolism* / Q000494:pharmacology; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008970:Molecular Weight; D011233:Precipitin Tests; D011487:Protein Conformation; D011971:Receptors, Immunologic / Q000302:isolation & purification*; D015375:Receptors, Interleukin-2; D013329:Structure-Activity Relationship; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D014162:Transfection
D003432:Cross-Linking Reagents; D007376:Interleukin-2; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2