The batman transcription unit. (A) Molecular map of the ban locus. The ban gene is transcribed from distal to proximal relative to the centromere. The two BamHI sites delimit the ban transcription unit as inferred from rescue assays using the pBB fragment (5,405 bp). Three lethal noncomplementing P[LacW] insertions are positioned in the first intron of ban. Df(2R)311a (24) uncovers the 5′ region of ban up to the first intron. This deficiency is the only one available that affects ban without affecting the neighboring Pcl gene, located 18 kb downstream of ban. The sequence corresponding to ORF127 is boxed on the ban transcript. (B) Northern blot analysis of embryonic (E) and third-instar larva (L) RNA probed with ban cDNA (top) and RP49 cDNA (bottom) as a control. (C) Multiple sequence alignment of D. melanogaster BTB/POZ proteins ordered according to decreasing similarity to BAN as calculated with the BLASTP algorithm. The alignment was generated using CLUSTALW. The cytoplasmic D. melanogaster Kelch protein and the human PLZF protein, for which a crystal structure has been determined (1), are set apart. The N-terminal nuclear BTB signature, characteristic of the Tramtrack subfamily and not conserved in Kelch (4, 87), is boxed. Conserved amino acids are boxed in black, and similarities are boxed in gray. The coordinates on the right refer to the position of the last amino acid included in the alignment from the sequences listed in GenBank. (D) Western blot analysis of larval proteins using the batC11 antibody. Extracts from third-instar larvae of the appropriate genotype were separated on sodium dodecyl sulfate-18% polyacrylamide gels. +/, w1118; da/UBF:da:Gal4/UBF larvae were obtained by crossing da:Gal4 homozygous flies to UBF homozygotes; Df/+, Df(2R)PC4/+ larvae; 2512/2512, banl(2)k02512/banl(2)k02512 escaper third-instar larvae were selected among the progeny of banl(2)k02512/CyO-GFP heterozygous flies based on the absence of GFP expression. Anti-MBF1 antibody (bottom panel) was used as a control for gel loading.