Ppz function in ubiquitin homeostasis is separable from its endocytic function. (A) WT or Δppz1Δppz2 mutant yeast cells (SUB280 strain background) harboring the indicated ubiquitin expression plasmids were plated on minimal media in the presence of canavanine (toxic arginine analogue). (B) The indicated yeast cells (SEY6210 background) containing either empty vector or PPZ1-FLAG vectors were analyzed for total cellular ubiquitin levels by immunoblot analysis. (C) Quantification of ubiquitin expression yeast cells (SEY6210 background) expressing the indicated Ppz expression plasmids. Error bars indicate standard deviation from multiple biological replicate experiments (n = 4). Statistical significance was calculated using a Student’s t test (P < 0.005).