Interleukin 9 (IL9) binds interleukin 9 (IL9R) and (IL2RG) to release IL9 signaling downstream cascade.
IL9R forms supramolecular clusters with Interleukin-2 receptors and MHC molecules in lipid rafts of human T lymphoma cells
IL2RG is essential for IL9 dependent growth signal transduction (Kimura et al. 1995). IL9R (glycoprotein of 64 kDa) has saturable and specific binding sites with a Kd of 100 pM (Renauld et al. 1992).
The activated IL9R complex employs the Tyrosine-protein kinase (JAK1) and Tyrosine-protein JAK3 (JAK3) for subsequent activation of the Signal transducer and activator transcription (STAT) factors STAT1, STAT3 and STAT5. The activated STATs form STAT5 dimers and STAT1:STAT3 heterodimers (Neurath & Finotto 2016, Li & Rostami 2010).