An associated molecule, p64, with IL-2 receptor beta chain. Its possible involvement in the formation of the functional intermediate-affinity IL-2 receptor complex.
We identified previously a membrane molecule, p64, which co-precipitates with the IL-2R beta-chain in human T cells. We have now investigated the biologic significance of p64 in the formation of the functional IL-2R complex with cell lines transfected with cDNA of IL-2R alpha- and/or beta-chains. Two functional parameters associated with IL-2R, IL-2 binding ability and association of p64 with the beta-chain, were examined. Two subclones, MOLT beta-11 and MOLT beta-12, of an IL-2R beta cDNA-transfected MOLT4 clone expressed similar numbers of IL-2R beta molecules on cell surfaces and bound to IL-2 with intermediate affinity. However, the numbers of IL-2 binding sites were significantly lower than those of IL-2R beta molecules and considerably different between the two subclones. The amount of p64 co-precipitated with IL-2R beta was proportional to numbers of the IL-2 binding sites in the two subclones. In addition, neither p64 co-precipitation nor IL-2 binding was detected in HeLa and COS7 cells transfected with IL-2R beta, and no p64 precipitation was seen even in those transfectants with both IL-2R alpha and beta cDNAs, which bind to IL-2 with high affinity but are not able to transduce intracellular signals. These results suggest the possibility that p64 associates with IL-2R beta and has an important role in formation of the functional IL-2R complex.
Takeshita
T
T
Department of Microbiology, Tohoku University School of Medicine, Sendai, Japan.
Ohtani
K
K
Asao
H
H
Kumaki
S
S
Nakamura
M
M
Sugamura
K
K
D001665:Binding Sites; D002460:Cell Line; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D015375:Receptors, Interleukin-2 / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D007376:Interleukin-2; D008565:Membrane Proteins; D015375:Receptors, Interleukin-2