A heat inducible promoter drives expression of sequence encoding the secreted extracellular domain of boss fused to the C-terminal 30 amino acids of the lacI repressor (includes the tetramerisation domain), resulting in the protein produced forming tetramers or higher order oligomers.
Heat induced expression during larval development of boss1/+ mutants causes stripes of ommatidia lacking R7 cells in adults.
Carried in plasmid "Exboss-Lac", expressed in S2 cells and oligomerisation of the fusion protein is studied.