Ub with K48 alone cannot support yeast viability and cumulative K to R substitutions lead to growth defects.
(A) The strategy for switching Ub expression in yeast.
(B) Expression of Ub-K48 as the only Ub source resulted in lethality (1X = ~100 cells).
(C) Growth curves of yeast strains expressing a single Ub gene under the PCUP1 promoter YPD medium.
(D) Comparison of His-myc-Ub monomer and conjugated forms in yeast strains. Total cell lysates (10 μg) were blotted with anti-myc antibodies.
(E) Quantification of polyUb linkages in yeast strains by MS. All values are normalized according to the levels in the wild-type strain and shown as mean and SEM.