This experiment by Hugh Pelham’s group, seen here on day 307 of #LMB365, demonstrates quality control of membrane proteins. A GFP-tagged SNARE protein (yellow) that normally goes to the plasma membrane in yeast (right) is completely redirected to the vacuole if an acidic residue is placed in the single C-terminal transmembrane domain (left). This aberrant transmembrane domain is recognised in the Golgi apparatus by a ubiquitin ligase, in this case Tul1, and ubiquitination of the protein directs it to the vacuole. The Nomarski image of the cells has been rendered as 3D elevation.
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