An improved Western blotting technique effectively reduces background

Ubiquitylation-mediated control of polar auxin transport: analysis of Arabidopsis PIN2 auxin transport protein

Reversible, covalent modification by the small protein ubiquitin acts in a variety of pathways controlling protein fate in virtually all aspects of cellular function. For example, ubiquitylation of plasma membrane proteins modulates their intracellular sorting and turnover, thereby decisively influencing crosstalk between cells and their environment. In recent years, experimental work performed with the model plant Arabidopsis thaliana demonstrated ubiquitylation of a number of plasma membrane proteins, including the auxin efflux carrier protein PIN2. By using solubilized membrane protein immunoprecipitation assays, we established quantitative approaches, suitable for analysis of PIN2 ubiquitylation and variations therein. Applicability of this robust approach is not restricted to PIN auxin carriers, but could be extended to analysis of further plant membrane proteins that are controlled by variations in their ubiquitylation status.