Composed of three distinct fragments. First, a 2240 bp His2Av PCR fragment encompassing 751 bp upstream of the His2Av translational initiation codon and the complete His2Av coding region up to the ultimate codon. This is fused to a second PCR fragment encompassing the mRFP1 coding region. A third PCR fragment encompassing 1690 bp of genomic His2Av 3' flanking DNA is cloned downstream of the His2Av-mRFP1 fusion protein.