The mitochondrial ferredoxin Yah1p of S. cerevisiae shares homology to bacterial [2Fe-2S] ferredoxins. The sequence alignment was prepared by using the multalin program (42). The four conserved cysteine residues (bold) are marked with arrows. Sc, S. cerevisiae; Hs, Homo sapiens; Rp, Rickettsia prowazekii; Rc, Rhodobacter capsulatus; Ec, Escherichia coli; Av, Azotobacter vinelandii; Hi, Haemophilus influenza; Adx, adrenodoxin; Fdx, ferredoxin.