Fig. 5. Mto1 and Mto2 form a stable complex in which Mto1 must contain both an intact CM1 region and an Mto2-binding region for normal function. (A) Anti-Mto2 immunoprecipitates from alp4-HA cells (strain KS1370), washed with the indicated concentrations of KCl and probed with antibodies to the proteins shown. (B) DIC images of representative diploid strains of the indicated genotypes described in C after growth to stationary phase and refeeding with fresh medium. Bar, 10 µm. (C) Cell morphology of diploids combining the different mto1 alleles shown in the rows and columns in trans (strains KS3786 x KS3780, KS3785 x KS3775, KS3786 x KS3789, KS3786 x KS3777, KS3795 x KS3784, KS3781 x KS3776, KS3780 x KS3784, KS3774 x KS3777, KS3775 x KS3784, KS3788 x KS3776, KS3789 x KS3784, KS3776 x KS3778, KS3777 x KS3784, reading from left to right). mto1-9A3 did not trans-complement any of the other mto1 mutant alleles, probably because mto1-9A3 is itself a partial loss-of-function allele, as shown in the morphology of mto1-9A3/mto1-9A3 homozygous diploids (see also Figs 1 and 2; supplementary material Movie 4). Other homozygous diploids were not constructed; ND, not determined.