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, surrounding the insertion site of the P-element that is responsible for the developmental 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 homologues of the mammalian mitochondrial trifunctional enzyme (thiolase), and the TAR DNA-binding protein-43 (TBPH), the first nonvertebrate member of the transmembrane 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 orient in a tail-to-tail manner with their 3' untranslated region sequences overlapping over 44 nucleotides. Thus the partial overlap and intraintronic organization permitted dense packing of the functional genes within a short segment of the genome. (C) 1999 Academic Press.