Co-internalization of the p55 and p70 subunits of the high-affinity human interleukin 2 receptor. Evidence for a stable ternary receptor complex

J Exp Med. 1988 Nov 1;168(5):1923-8. doi: 10.1084/jem.168.5.1923.


The high-affinity IL-2-R complex is composed of at least two distinct IL-2-binding subunits, including p55 (Tac, IL-2-R alpha) and p70 (IL-2-R beta). Using a radiolabeled mAb specific for the p55 receptor subunit and cells expressing a homogeneous population of high-affinity binding sites, we demonstrate that p55 is co-internalized with p70 after IL-2 binding to the receptor complex. Endocytosis of p55 depends upon the presence of IL-2 in a form capable of effectively interacting with the p70 subunit. Whether IL-2 is required for high-affinity receptor assembly or triggering of the internalization of preassembled receptors remains unresolved. Together, these findings support the existence of a stable, high-affinity human IL-2-R membrane complex composed of at least the p55 and p70 receptor subunits and IL-2.

MeSH terms

  • Binding Sites
  • Cell Line
  • Endocytosis*
  • Humans
  • Interleukin-2 / metabolism
  • Macromolecular Substances
  • Molecular Weight
  • Receptors, Interleukin-2 / physiology*
  • Receptors, Interleukin-2 / ultrastructure
  • T-Lymphocytes / physiology*


  • Interleukin-2
  • Macromolecular Substances
  • Receptors, Interleukin-2