| Legend: BMP and activin signaling in
Drosophila. The BMP ligands Dpp, Gbb
and Scw, act through the type I receptors Tkv or
Sax, resulting in phosphorylation of Mad, its
association with the co-Smad Med, translocation of the
complex into the nucleus, and regulation of gene expression. The
type II receptors Put and Wit display dual
specificity and function in both the BMP and activin pathways. An
activin pathway that involves the type I receptor Babo and
dSmad2 has also been identified in Drosophila.
The ligand, dActivin, signals through Babo.
Phylogenetic analysis of Mav, Alp and Myo,
does not allow their assignment to a particular pathway (Parker,
2004). |
