Glucose-induced Ubiquitylation and Endocytosis of the Yeast Jen1 Transporter

Protein ubiquitylation is essential for many events linked tointracellularproteintrafficking.Despitethesignificanceofthisprocess, the molecular mechanisms that govern the regulationof ubiquitylation remain largely unknown. Plasma membranetransporters are subjected to tightly regulated endocytosis, andubiquitylation is a key signal at several stages of the endocyticpathway. The yeast monocarboxylate transporter Jen1 displaysglucose-regulatedendocytosis.Weshowherethatcaseinkinase1-dependentphosphorylationandHECT-ubiquitinligaseRsp5-dependent ubiquitylation are required for Jen1 endocytosis.UbiquitylationandendocytosisofJen1areinducedwithinmin-utesinresponsetoglucoseaddition.Jen1ismodifiedatthecellsurface by oligo-ubiquitylation with ubiquitin-Lys