Growth of TPK mutants on different media. Strains were grown on YPD (iron-rich, glucose medium), high-glucose/low-iron media (low iron), YPEG (ethanol glycerol medium), and YPEG containing the iron chelator ferrozine (+ferr). From the top, the strains are 10560-2B (wild type), LRY765 (tpk1), LRY590 (tpk2), and LRY636 (tpk3).