THE PORE-FORMING AND CYTOPLASMIC DOMAINS OF THE NEUROGENIC GENE-PRODUCT, BIG BRAIN, ARE CONSERVED BETWEEN DROSOPHILA-VIRILIS AND DROSOPHILA-MELANOGASTER

The Drosophila BIG BRAIN (BIB) protein functions critically in the det ermination of neuroblasts in the embryonic ectoderm and many other cel l types. BIB is a member of the MIP family of transmembrane channel pr oteins. The conserved channel domain of BIB is flanked by amino- and c arboxy-terminal cytoplasmic domains of unique sequence, which comprise over two-thirds of the protein. To determine whether the cytoplasmic domains of BIB are important for BIB function, we have cloned and sequ enced the bib gene of D. virilis and compared it with that of D. melan ogaster. Here we report that the channel domain and both cytoplasmic d omains are highly conserved between the two species. The conservation of the cytoplasmic domains indicates that they are critical to BIB fun ction. bib transcripts are found in similar patterns in both species, indicating that the developmental function(s) of BIB have also been co nserved. (C) 1997 Elsevier Science B.V.