STRUCTURE AND EXPRESSION OF THE ANTIGEN 5-RELATED GENE OF DROSOPHILA-MELANOGASTER

The Agr gene of Drosophila melanogaster was localized to the X chromos ome 12F region between the Netrin B and rutabaga genes. A P1 clone con taining this area was identified, and restriction sites within this cl one were mapped. The entire Agr gene and some flanking region were seq uenced, and the transcription start site was determined. The gene was 938 bp in length and included a 108 bp intron, dividing the coding reg ion into a 140 bp 5' exon and a 690 bp 3' exon. The 5' untranslated re gion (UTR) was 23 bp in length and the 3' UTR 36 bp. Gene expression w as initiated during late embryogenesis and was also observed during th e larval, prepupal, and adult stages. Expression was found only in the outer layer of the proventriculus, a structure located at the fore- a nd midgut junction. Deletion of the Agr gene had no effect on proventr icular morphogenesis in embryos. The Agr expression pattern within the proventriculus suggests that it encodes a component of the peritrophi c matrix, a tubular envelope produced by the proventriculus and which lines the midgut. Sequences similar to the Agr coding region were dete cted in other dipteran species, suggesting that the function of the Ag r gene product is conserved. (C) 1998 Elsevier Science Ltd. All rights reserved.