Figure 4.

Quantification of ubiquitin levels in R6/2‐Ubc mice by indirect competitive ELISA. (A) Treatment of brain samples with the ubiquitin‐ specific protease Usp2‐cc successfully converts all visible ubiquitin linkages into monomeric ubiquitin. Blots were stripped and reprobed with α‐tubulin to show equal loading of protein. (B) Standard curve using precise ubiquitin concentrations shows the indirect competitive ELISA is linear in the range of 2–500 ng of ubiquitin. (C) Total ubiqutin levels in the R6/2 brain are not significantly different from those in WT, whereas the loss of one Ubc allele does cause a small but significant reduction in ubiquitin levels. Ubiquitin levels are not significantly different between Ubc+/− mice and R6/2; Ubc+/− mice treatment with Usp2‐cc increases measurable ubiquitin as the antibody preferentially detects monomeric ubiquitin. Error bars represent standard errors of the mean.