ATT, A TARGET FOR REGULATION BY TRA2 IN THE TESTES OF DROSOPHILA-MELANOGASTER, ENCODES ALTERNATIVE RNAS AND ALTERNATIVE PROTEINS

We have identified a gene, alternative testis transcripts (att), which is alternatively expressed, at both the RNA and protein levels, in te stes and somatic tissues. The testis-specific RNA differs from somatic RNAs in both promoter usage and RNA processing and is dependent on th e function of the transformer 2 gene. The differences between the soma tic and testis RNAs have substantial consequences at the protein level . The somatic RNAs encode a protein with homology to the mammalian Gra ves' disease carrier proteins. The testis RNA lacks the initiation cod ons used in somatic tissue and encodes two different proteins. One of these begins in a testis-specific exon, uses a reading frame different from that for the somatic protein, and is completely novel. The other protein initiates translation in the frame of the somatic RNA at a Le u CUG codon which is within the open reading frame for the somatic pro tein. This produces a novel truncated version of the Graves' disease c arrier protein-like protein that lacks all sequences N terminal to the first transmembrane domain.