Supplemental Experimental Procedures

Radiolabeled Chemicals; NADPH from Roche; horseradish peroxidase-conjugated, affinity purified donkey anti-rabbit and anti-mouse IgG from Jackson ImmunoResearch and Prestained Protein Standards from Bio-Rad. Protease inhibitors (leupeptin [10 µg/ml]; pepstatin A [5 µg/ml]; PMSF [1 mM]) were used at the indicated concentrations and obtained from Sigma. For experiments involving Sty1, cells were harvested by filtration (Shiozaki and Russell, 1997). Standard genetic manipulations and molecular biology techniques were performed as described (Hughes et al., 2005). Construction of Hmg1 mutant strains and integrating plasmid