A structure and function analysis of the Drosophila tissue polarity gene: frizzled

Frizzled (fz) is one of several Drosophila genes required to establish the polarity of the bristles and hairs that decorate the cuticle of the fly. fz has separately mutable cell non-autonomous and cell autonomous functions that are revealed in mosaic analysis of the wing. The predicted topology of fz places fz in the seven transmembrane-spanning class of integral membrane proteins, most of which are G protein-coupled receptors. I have taken evolutionary and structure-function approaches to define the fz protein domains that are required for intercellular and intracellular polarity signalling functions. I report here that the Drosophila virilis fz homolog is 92% identical to that of Drosophila melanogaster, and that this homolog is functional in D. melancgaster transgenic flies. In addition, sequence analysis of several cell non-autonomous and cell autonomous fz alleles demonstrates that while the non-cell autonomous alleles map throughout the protein, the cell autonomous alleles all map to a proline residue within the first putative cytoplasmic domain.

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