gain of function allele

Insertion in an intron of the Lpin gene, to the 3' of the kermit gene. The insertion causes the production of 2305bp chimeric mRNA which consists of part of the untranslated first exon of Lpin/kermit and the second through sixth exons of the w gene present in the inserted element. The open reading frame of the chimeric transcript encodes a 770 amino acid sequence that corresponds to the w protein lacking the first 23 amino acids. Expression of the Lpin-K isoform is abolished by the insertion in the tissues studied (central nervous system, intestinal tract and Malpighian tubules), while expression of the chimeric transcript is virtually identical to that of the Lpin-K isoform observed in wild-type flies. The insertion also results in an increase in the expression of kermit in the intestinal tract and Malpighian tubules compared to wild type. Analysis of expression patterns of the Lpin-K isoform, kermit and the chimeric transcript containing w in flies carrying P{SUPor-P}Lpin^KG00562 indicates that the lethality seen in the P{SUPor-P}Lpin^KG00562 line is associated with overexpression of kermit in this line.