TY - JOUR
T1 - Stepwise formation of the high-affinity complex of the interleukin 2 receptor
AU - Saito, Yuji
AU - Ogura, Toshihiko
AU - Kamio, Masanori
AU - Sabe, Hisataka
AU - Uchiyama, Takashi
AU - Honjo, Tasuku
PY - 1990/12/1
Y1 - 1990/12/1
N2 - The interleukin 2 receptor (IL-2R) is composed of at least two polypeptides-a 55 kd protein (the L chain, p55, or α chain) and a 75 kd protein (the H chain, p75 or β chain). The high-affinity binding of IL-2 results in the formation of a ternary complex consisting of IL-2 and the L and H chains. We found that the rate of high-affinity complex formation at 0°C was about one-third of that at 37°C. The reduction of high-affinity complex formation rate at lower temperatures correlates with the reduction of lateral diffusion within the membrane at lower temperatures. An anti-H chain antibody (2RB) inhibited the formation of the high-affinity complex at 0°C but not at 37°C. We studied the kinetics of the high-affinity complex formation at 37°C after the preincubation of ATL-2 cells with the 2RB antibody and IL-2 at 0°C. We found that the amount of IL-2 complex formed initially at 0°C was almost equivalent to the amount of high-affinity complex formed by subsequent incubation at 37°C. These results suggest that the IL-2̇L complex might be converted to the high-affinity IL-2R complex. Similar experiments using YTC3 cells, which express a smaller number of L chains, showed slower rates of high-affinity complex formation, in agreement with the affinity conversion/stepwise binding model.
AB - The interleukin 2 receptor (IL-2R) is composed of at least two polypeptides-a 55 kd protein (the L chain, p55, or α chain) and a 75 kd protein (the H chain, p75 or β chain). The high-affinity binding of IL-2 results in the formation of a ternary complex consisting of IL-2 and the L and H chains. We found that the rate of high-affinity complex formation at 0°C was about one-third of that at 37°C. The reduction of high-affinity complex formation rate at lower temperatures correlates with the reduction of lateral diffusion within the membrane at lower temperatures. An anti-H chain antibody (2RB) inhibited the formation of the high-affinity complex at 0°C but not at 37°C. We studied the kinetics of the high-affinity complex formation at 37°C after the preincubation of ATL-2 cells with the 2RB antibody and IL-2 at 0°C. We found that the amount of IL-2 complex formed initially at 0°C was almost equivalent to the amount of high-affinity complex formed by subsequent incubation at 37°C. These results suggest that the IL-2̇L complex might be converted to the high-affinity IL-2R complex. Similar experiments using YTC3 cells, which express a smaller number of L chains, showed slower rates of high-affinity complex formation, in agreement with the affinity conversion/stepwise binding model.
KW - Affinity conversion
KW - Stepwise binding model
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U2 - 10.1093/intimm/2.12.1167
DO - 10.1093/intimm/2.12.1167
M3 - Article
C2 - 2090200
AN - SCOPUS:0025609656
VL - 2
SP - 1167
EP - 1177
JO - International Immunology
JF - International Immunology
SN - 0953-8178
IS - 12
ER -