Fig. 1. ARG8^m reporter constructs at COX1. The mitochondrial genes, predicted translation products, and arginine and respiratory phenotypes of strains bearing wild-type nuclear genomes are indicated. The open boxes represent the COX1 and ARG8^m structural genes. The COX1 5′-UTL and 3′-UTR are indicated as solid boxes. The black triangles indicate the processing site for the pre-Arg8p matrix-targeting signal. In the COX1(1–512)::ARG8^m construct, the ARG8^m gene was fused in-frame to the complete, 512 COX1 codons, such that the COX1 stop codon was replaced by the initial methionine of the ARG8^m gene. In the cox1Δ::ARG8^m construct, the ARG8^m gene replaced the COX1 codons, and was precisely fused to the COX1 5′-UTL and 3′-UTR.