title: Trans-splicing as a novel mechanism to explain interallelic complementation in Drosophila.
abstract: Two mutant alleles of the same gene, each located in one of the two homologous chromosomes, may in some instances restore the wild-type function of the gene. This is the case with certain combinations of mutant alleles in the mod(mdg4) gene. This gene encodes several different proteins, including Mod(mdg4)2.2, a component of the gypsy insulator. This protein is encoded by two separate transcription units that can be combined in a trans-splicing reaction to form the mature Mod(mdg4)2.2-encoding RNA. Molecular characterization of complementing alleles shows that they affect the two different transcription units. Flies homozygous for each allele are missing the Mod(mdg4)2.2 protein, whereas wild-type trans-heterozygotes are able to synthesize almost normal levels of the Mod(mdg4)2.2 product. This protein is functional as judged by its ability to form a functional insulator complex. The results suggest that the interallelic complementation in the mod(mdg4) gene is a consequence of trans-splicing between two different mutant transcripts. A conclusion from this observation is that the trans-splicing reaction that takes place between transcripts produced on two different mutant chromosomes ensures wild-type levels of functional protein.
authors.affiliation: Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Fabien
authors.initials: F
authors.lastname: Mongelard
authors.forename: Mariano
authors.initials: M
authors.lastname: Labrador
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Baxter
authors.forename: Tatiana I
authors.initials: TI
authors.lastname: Gerasimova
authors.forename: Victor G
authors.initials: VG
authors.lastname: Corces
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics*; D005816:Genetic Complementation Test; D007150:Immunohistochemistry; D017422:Sequence Analysis, DNA; D020040:Trans-Splicing; D014157:Transcription Factors / Q000235:genetics*; D014921:Wings, Animal
chemical_list: D029721:Drosophila Proteins; D014157:Transcription Factors; C101384:mod(mdg4) protein, Drosophila