Interleukin 6 signal transducer (gp130) phosphotyrosine 759 motif (gp130 pY759)

The gp130 phosphotyrosine motif pY759 (pYSTV) is a critical regulatory site located within the cytoplasmic tail of the Interleukin 6 signal transducer (gp130), the shared signaling subunit for the IL-6 family of cytokines (UniProt P40189). Upon cytokine-induced activation of the receptor complex, Janus kinases (JAKs) phosphorylate the tyrosine residue at position 759, creating a docking site for the SH2 domains of the protein tyrosine phosphatase SHP-2 and the feedback inhibitor SOCS3 (PubMed: 11017147). This motif is essential for the negative feedback regulation of the JAK/STAT3 pathway; SOCS3 binding inhibits JAK activity and promotes receptor degradation, effectively terminating the inflammatory signal (PubMed: 15123770). Conversely, the recruitment of SHP-2 to this site initiates the Ras/MAPK signaling cascade, demonstrating the motif's role as a molecular switch between different signaling pathways. Mutations in this motif, such as the Y759F substitution, prevent SOCS3 recruitment, leading to prolonged STAT3 activation and the development of chronic inflammatory and autoimmune conditions like rheumatoid arthritis (PubMed: 12482851). While current clinical therapies like Tocilizumab and Sarilumab target the broader IL-6 receptor complex, the pY759 motif is a focal point for research into specific modulators of cytokine signaling and the molecular mechanisms of inflammatory disease.

Other names

gp130 Y759IL6ST pY759SHP-2 binding site of gp130SOCS3 binding site of gp130pYSTV motifTyr759 of gp130

The phosphorylated Y759 residue (pY759) serves as a high-affinity docking site for the SH2 domains of SOCS3 and SHP-2. Binding of SOCS3 leads to the direct inhibition of Janus kinases (JAKs) and targets the receptor complex for proteasomal degradation, thereby terminating STAT3 signaling. Simultaneously, recruitment of SHP-2 (PTPN11) triggers the Ras/MAPK/ERK signaling pathway.