Fig. 2. tpc1Δ mutant is auxotrophic for thiamine. (A) Growth behavior of tpc1Δ in various conditions. Four-fold serial dilutions of wild-type and tpc1Δ mutant strains were plated on solid SM supplemented with 2% glucose. Where indicated, 0.4 mg/l thiamine, 4 mg/ml HET, 4 mg/ml thiazole, 340 µg/ml valine (VAL) or 430 µg/ml isoleucine (ILE) was also present. (B) The expression level of Tpc1p is independent of the presence of thiamine in the SM medium. Equal amounts of mitochondrial lysates from wild-type cells grown on galactose-supplemented SM with or without thiamine (Th) were separated by SDS–PAGE, transferred to nitrocellulose and immunodecorated with the antiserum directed against Tpc1p.