Figure 1.

Expression of UBB⁺¹ in Yeast and Its Effect on UPS Activity

(A) Proteins were expressed for 1, 2, or 3 days and determined by immunoblotting of cell extracts using antibodies directed against the N-terminal FLAG-tag, or the specific C terminus of UBB⁺¹. Hexokinase (Hxk) was used as loading control. #, unspecific protein band; fl-UBB⁺¹, full-length UBB⁺¹; tUBB⁺¹, truncated UBB⁺¹.

(B) The level of polyubiquitylated proteins and of UBB⁺¹ in cell extracts was determined by immunoblotting using an antibody directed against ubiquitin. ^∗Uncharacterized ubiquitin variant.

(C) Quantification of (B). The levels of polyubiquitylated proteins of cells transformed with vector controls were set to 100% in every experiment.

(D) Cellular level of ubiquitin-G76V-GFP upon UBB⁺¹ expression. GFP fluorescence (relative fluorescence units, RFUs) was normalized to optical densities (OD₆₀₀).

Data: percentage change values (C) and mean values (D), respectively. Error bars: SE. p values: ^∗p < 0.05, ^∗∗p < 0.01. See Table S1 and Figure S1.