UASp regulatory sequences drive expression of a truncated form of chb that encodes only the TOG1, TOG2 and Linker regions (the linker includes the SxIP motif).
Scer\GAL4ppk.PU/chbTOG1,2-Linker.UASp rescues chb4
chbTOG1,2-Linker.UASp/Scer\GAL4477 rescues chb4/chb464