Membrane Transport in Yeast
Eukaryotic cells use membrane-bound carriers to secrete and internalize macromolecules. The export of macromolecules starts at the endoplasmic reticulum (ER) and the direction of transport from the ER via the Golgi to plasma membrane is called forward or anterograde transport. Transport in the opposite direction helps to compensate for the loss of membrane material and proteins from organelles like ER and Golgi apparatus. Vesicles and tubules act as carriers both in anterograde and retrograde traffic. The focus of our work is the membrane traffic in the yeast Saccharomyces cerevisiae. It is very easy to introduce genetic modifications into this simple eukaryote and this facilitates the analysis of cellular processes very much.
Our main interest is the retrograde transport from the Golgi to the ER. This transport involves vesicles that carry COP-I coats. The formation of this proteinaceous coat around the membrane is necessary for budding of the vesicles at the Golgi membrane. The removal of this coat may take place at the target membrane, the ER. The presence of the COP-I coat and its recognition by an ER-resident tethering complex seems to be important to direct the vesicles to the right target membrane. We want to analyze how anterograde and retrograde transport are linked at the ER.