Figure 1. The Drosophila JAK-STAT pathway. Three Unpaired (Upd) ligands here collectively referred to as Upd (orange) activate a dimeric receptor Domeless (Dome) (magenta). This results in activation of the JAK Hopscotch (Hop) (green), leading to tyrosine phosphorylation of Dome. The phosphorylated receptor/JAK complex phosphorylates STAT92E dimer (blue) on Y711, generating an active STAT92E dimer. A consensus TTCNNNGAA site is bound by the activated STAT92E dimer, leading altered gene expression. One of the best-characterized STAT92E target genes is Socs36E, encoding a negative regulator of JAK/receptor activity (pink). A second receptor Eye Transformer (ET) (also called Latran [Lat]), referred to as ET/Lat (red), forms heterodimers with Dome and inhibits JAK-STAT signaling. Brown circles represent phospho-tyrosine residues.