B. Schnepp et al., VEIN IS A NOVEL COMPONENT IN THE DROSOPHILA EPIDERMAL GROWTH-FACTOR RECEPTOR PATHWAY WITH SIMILARITY TO THE NEUREGULINS, Genes & development, 10(18), 1996, pp. 2302-2313
The activation signal from tyrosine kinase receptors, such as the epid
ermal growth factor receptor (EGFR), is relayed via a highly conserved
intracellular pathway involving Ras, Raf, and MAPK. In Drosophila, th
e EGFR and components of the intracellular pathway are broadly express
ed, yet receptor activation evokes tissue-specific cell responses. Ext
racellular events that lead to receptor activation are one mechanism b
y which signaling is modulated. Here we show molecular and genetic evi
dence that Drosophila vein (vn) encodes a candidate EGFR ligand and th
at vn expression is spatially restricted. Consequently, vn may promote
tissue-specific receptor activation. Unlike two other ligands, Gurken
(Grk) and Spitz (Spi), which are transforming growth factor alpha-lik
e proteins, Vn has both an immunoglobulin-like and an EGF-like domain.
This combination of domains mirrors those in the vertebrate neureguli
ns that bind EGFR relatives.