To investigate the role of NatB-mediated N-terminal acetylation in regulating protein stability in Arabidopsis thaliana, polyubiquitinated proteins were determined by mass spectrometry in wild type (Col-0) and naa20-cr1 mutant after enrichment by UbiQaputre-Q matrix (Enzo life Sciences).Proteins with increased or decreased abundance in the mutant were analyzed compared to the wild type.