Interleukin-3 binding to the murine βIL-3 and human βc receptors involves functional epitopes formed by domains 1 and 4 of different protein chains

Abstract

Interleukin-3 (IL-3) is a cytokine produced by activated T-cells and mast cells that is active on a broad range of hematopoietic cells and in the nervous system and appears to be important in several chronic inflammatory diseases. In this study, alanine substitutions were used to investigate the role of residues of the human β-common (hβc) receptor and the murine IL-3-specific (βIL-3) receptor in IL-3 binding. We show that the domain 1 residues, Tyr15 and Phe79, of the hβc receptor are important for high affinity IL-3 binding and receptor activation as shown previously for the related cytokines, interleukin-5 and granulocyte-macrophage colony-stimulating factor, which also signal through thi..