UNIQUE GENE ORGANIZATION - ALTERNATIVE SPLICING IN DROSOPHILA PRODUCES 2 STRUCTURALLY UNRELATED PROTEINS

The Ub80 gene in eukaryotes produces a ubiquitin fusion protein in whi ch ubiquitin is fused in frame to a tail protein (Redman and Rechstein er, 1988; Finley et al., 1989; Barrio et al., 1994). The tail protein is incorporated into the ribosome, and ubiquitin is thought to act as a chaperone. The DUb80 gene of Drosophila melanogaster was cloned by B arrio et al. (1994) and contains a 5'-untranslated exon, followed by a large intron and then the first coding exon. We report that the large intron of DUb80 contains an open reading frame, which produces a 259- aa protein (1P259) that is conserved in eukaryotes from yeast to mamma ls. Transcription of the DUb80 and 1P259 mRNAs begins at the same star t sites. However, alternate splicing of the primary transcript produce s two structurally unrelated proteins. This is the second reported ins tance of two structurally unrelated proteins being produced via altern ate splicing, suggesting that this form of genomic organization may be more common than previously thought. (C) 1997 Elsevier Science B.V.