(B) The Slx5-SIMs and Slx5-Md are required for Euc1 ubiquitylation. NiNTA-PDs for His-ubiquitin as in (A). All strains expressed wild-type 3FLAGEuc1 from plasmids under the ADH promoter and His-ubiquitin. Slx5 constructs were expressed from plasmids under control of the endogenous promoter. WBs were probed as described in (A), Slx5-levels were probed using an HA antibody. Asterisk denotes a non-specific band. Slx5-SIM*: SIMs 1-4 were mutated as described (Xie et al, 2010), for SIM5, aa 477-479 (IIV) were mutated to alanines. To avoid possible mislocalization by deletion of the Slx5-Md, which overlaps with a putative NLS (Westerbeck et al, 2014), an N-terminal NLS was fused to all constructs. See Appendix Fig. S7C for HU complementation. 