Fig. 2. Positive regulators of Drosophila JAK/STAT signalling. (A) Three UPD-related ligands, each of which contain N-terminal signal sequences (S) and have predicted N-linked glycosylation sites (dots). (B) DOME contains fibronectin type III-like repeats (FN3) (characteristic of cytokine receptors), a transmembrane region (blue box) and a coiled-coil domain (cc). (C) Hopscotch contains an N-terminal FERM (4.1, ezrin, radixin, moesin) domain found in all JAKs that is required for association with the receptor (Usacheva et al., 2002), an SH2 domain, a regulatory pseudo-kinase domain and a Tyr kinase (Y-kinase) domain. (D) STAT92E contains a N-terminal domain found in all STATs that mediates tetramerisation (Johnson et al., 1999; Vinkemeier et al., 1998), a coiled-coil region and a DNA-binding domain (DBD). An SH2 domain is also present, and is required for receptor binding and dimerisation. In mammalian STATs, the C terminus also contains a transcriptional activation domain. In NSTAT92E, the absence of the N-terminal region produces a protein that acts as a dominant negative (Henriksen et al., 2002). (E) BRWD3 contains eight WD40 motifs and two BROMO domains, which are frequently present in chromatin-associated proteins. Proteins and domains are shown to scale.