The Drosophila melanogaster 60A chromosomal division is extremely dense with functional genes: Their sequences, genomic organization, and expression

We cloned and sequenced genomic DNA contigs spanning over 45 kb, surroundin g the insertion site of the P-element that is responsible for the developme ntal defects in the hen and barbie (ken) mutant of Drosophila. This region harbors 10 functional transcription units, in addition to the already well- characterized TGF beta-60A gene. These include the genes, undefined 1 (UD1) , UD2, and UD3, each coding for proteins of unknown function, the hen gene encoding a new Kruppel-like putative transcription factor, the fly homologu es of the mammalian mitochondrial trifunctional enzyme (thiolase), and the TAR DNA-binding protein-43 (TBPH), the first nonvertebrate member of the tr ansmembrane 4 superfamily (TM4SF) gene, a new homeodomain gene, and a gene coding for a putative nuclear binding protein (PNBP) that is homologous to maleless, and a Copia-like element, UD3 exists in an intron of the maleless homologue, yet is expressed independent of it. The UD1 and TM4SF genes ori ent in a tail-to-tail manner with their 3' untranslated region sequences ov erlapping over 44 nucleotides. Thus the partial overlap and intraintronic o rganization permitted dense packing of the functional genes within a short segment of the genome. (C) 1999 Academic Press.