A heat-inducible Hsp70 promoter drives expression of a constitutively active form of btl in which the ligand-binding extracellular domain has been replaced with the dimerization domain of the bacteriophage λ cI repressor (to induce constitutive dimerization of the encoded protein).
air sac tracheoblast of dorsal mesothoracic disc & filopodium
More proliferating air sac tracheoblasts are seen in third instar wing discs of btlhs.T:λ\cI-DD larvae after heat shock than in wild type controls. No change in the numbers of filopodia formed by air sac tracheoblasts occur in these larvae after heat shock. However, the filopodia that form are shorter than in wild-type.
Heat induced expression in wild type stage 14 embryos causes disruption of tracheal primary branch development, the dorsal trunk is incompletely fused and abnormal primary branches and ectopic secondary branches are observed in most stage 16 embryos. Induced expression in heterozygous btlH82Δ3 embryos exaggerates the dorsal trunk defects. Heat induced coexpression of btlKR.hs and btlhs.T:λ\cI-DD at stage 11 almost completely blocks primary branching and coexpression at stage 12 rescues the secondary branching defects of btlKR.hs embryos.
Heat induced coexpression of btlKR.hs and btlhs.T:λ\cI-DD at stage 11 almost completely blocks primary branching and coexpression at stage 12 rescues the secondary branching defects of btlKR.hs embryos.
Encodes a constitutively active receptor tyrosine kinase (RTK).