An unstable fusion protein consisting of the first 273 amino acids of ftz, the GFP coding region and six copies of Tag:MYC is expressed under the control of an Orc1 promoter fragment that includes approximately 2.3kb of upstream sequences and 60bp downstream of the transcription start site. The fusion protein also contains a nuclear localisation signal.
Encodes an unstable protein, the half-life of which is short with respect to the length of the cell cycle. Accumulation of the protein therefore monitors newly synthesised protein, allowing examination of cell cycle-regulated transcription in vivo.