Synthetic Peptides from the Region 30-54 of the Interleukin-2 Receptor β-Chain (IL-2Rβ)Affect IL-2 Binding to Human T-Cells

The interleukin-2 receptor β-chain (IL-2Rβ) is responsible for the IL-2 internalization and signal transduction. To identify domains from the IL-2Rβ extracellular region which are involved in ligand receptor interactions, eight peptides of 8 to 25 amino acids corresponding to IL-2Rβ sequence 30-54 were synthesized. Their biological effect was tested with [125I]IL-2 equilibrium binding to PHA-blasts. Preincubation of [125I]IL-2 with peptides IL-2Rβ (35-54) and (30-42) affects IL-2 binding to both high and intermediate affinity receptors by revealing a greater number of active sites with lower affinity.