Fig. 1. Structure of GFP reporter transgenes. Boxes represent exons, and solid bars represent introns. Unfilled and filled circles represent translation start and stop codons, respectively. Arrows show transcription start sites. All the transgenes are driven by Ubi-p63E promoter and have Ubi-p63E 5'UTR with an intron (intron not shown) which is 5' to the open reading frame (ORF) starting at ATG. The ORF encodes a Myc-tag fusion GFP. In UGA and UGH, the ORF is not interrupted by an intron, whereas in UgGA and UgGH, a generic intron GI (Mottes and Iverson, 1995) is inserted within the ORF. In UnGA and UnGH, an alternatively spliced intron from nrg (nASI) is inserted at the same position as GI, necessitating neuronspecific splicing of the intron for GFP expression. UGA, UgGA, and UnGA have Act5C 3'UTR, while UGH, UgGH, and UnGH have Hsp70Ab 3'UTR. This figure is not drawn to scale.