Erhardt I, Lischke A, Sebald W, Friedrich K
Theodor-Boveri-Institut für Biowissenschaften (Biozentrum), Physiologische Chemie II, Am Hubland, Würzburg, Germany.
FEBS Lett. 1998 Nov 13;439(1-2):71-4. doi: 10.1016/s0014-5793(98)01341-6.
The bipartite human interleukin-4 (IL-4) receptor was functionally expressed in murine pro-B cells and activated by human IL-4 to evoke intracellular signaling. Mutual association of signal transducing proteins within the receptor complex was then studied in dependence of ligand stimulation. Besides ligand-induced receptor heterodimerization and contacts of the two IL-4 receptor subunits alpha and gamma with Janus kinases JAK1 and JAK3 a prominent constitutive binding between JAK1 and signal transducer and activator of transcription STAT5 was detected. Since both these proteins become phosphorylated in response to IL-4 receptor stimulation, the influence of tyrosine phosphorylation on their mutual contact was analyzed. Association of JAK1 and STAT5 was found to occur exclusively between unphosphorylated proteins.
