During leptin signaling, each of the phosphorylated tyrosine residues on the long form of the
leptin receptor (LRb) mediates distinct signals. Phosphorylated Tyr 1138 binds STAT3 to
mediate its tyrosine phosphorylation and transcriptional activation, while phosphorylated Tyr
985 binds the tyrosine phosphatase SHP-2 and reportedly mediates both activation of ERK
kinases and inhibition of LRb-mediated STAT3 activation. We show here that although
mutation of Tyr 985 does not alter STAT3 signaling by erythropoietin receptor-LRb (ELR) …