Interleukin-3 and granulocyte-macrophage colony-stimulating factor receptor signal transduction

The cytokines, interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF), share many similar activities on cells of the hemopoietic system. Cloning of the receptors for IL-3 and GM-CSF revealed that these two cytokines utilize receptors consisting of a ligand-specific alpha unit and a beta subunit which is shared. Neither subunit contains intrinsic tyrosine kinase activity, but deletion analysis of the beta subunit cytoplasmic domain has defined certain regions which are important for signal transduction.