Escherichia coli DH5a was used to amplify plasmid DNA. Transformations of E. coli were performed as described previously using the calcium chloride method (22) . Yeast cells were transformed using the alkali cation method (23) . Yeast strains used in this study are shown in Supplementary Table S1 . Yeast were grown on YPAD and synthetic complete media (HÀ) (24) . yRP2056, yRP2077 were kind gifts from R. Parker. YJB2659 (generously provided by Judith Berman) was sporulated and strains JD1276, JD1281, JD1287 and JD1288 were obtained by tetrad dissection.