The gene structure of the Drosophila melanogaster proto-oncogene, kayak, and its nested gene, fos-intronic gene.
We present herein a new model for the structure of the Drosophila kayak gene as well as preliminary data on the functional differences of its various isoforms. kayak is a homolog of the human proto-oncogene, c-fos. kayak has three different starts of transcription, and therefore promoters (P)kay-alpha, (P)kay-beta and (P)kay-gamma. These three promoters lead to four different transcripts: kay-alpha, kay(sro), kay-beta and kay-gamma. (P)kay-alpha produces two different transcripts: kay-alpha and kay(sro) where the other two promoters, (P)kay-beta and (P)kay-gamma, produce a single transcript each. The transcripts kay-alpha, beta and gamma all splice into the mainbody of the kay gene, which codes for the DNA binding domain and leucine zipper; kay(sro) is not spliced. Also, within this region is a nested gene, fos-intronic gene (fig) which is transcribed in the opposite direction. fig codes for a predicted PP2C phosphatase. fig has two different promoters which produce two different transcripts, both in the same reading frame, fig-alpha and beta. This is an unusual gene structure for Drosophila. Only 13% of Drosophila genes have multiple promoters and only 7% have a nested gene. RT-PCR was performed on each transcript to determine the relative amounts of each RNA produced. All spliced kay transcripts appear to have equal abundance. The unspliced kay(sro) transcript has a lower abundance than kay-alpha. Both fig transcripts are also detected in all stages tested. Lethal phase analysis and complementation testing suggest that the three isoforms of kayak may have different functions.
Hudson
Stephanie Gidget
SG
Arizona State University, School of Life Science, Tempe, Arizona 85287-4501, USA.
Goldstein
Elliott S
ES
D020121:5' Untranslated Regions; D000818:Animals; D003001:Cloning, Molecular; D018387:Codon, Initiator; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics*; D007438:Introns; D009154:Mutation; D020033:Protein Isoforms; D000090063:Proto-Oncogene Mas; D011519:Proto-Oncogenes; D020133:Reverse Transcriptase Polymerase Chain Reaction
D020121:5' Untranslated Regions; D018387:Codon, Initiator; D029721:Drosophila Proteins; C000715470:MAS1 protein, human; D020033:Protein Isoforms; D000090063:Proto-Oncogene Mas; C435749:kay protein, Drosophila