Evidence That Protein Disulfide Isomerase in Yeast <i>Saccharomyces cerevisiae</i> Is Transported from the ER to the Golgi Apparatus

Newly synthesized membrane and secretory proteins in cells undergo folding the endoplasmic reticulum with introduction of disulfide bonds acquire correct three-dimensional structure. Disulfide are especially important for protein folding. It has been thought that formation eukaryotes is mainly carried out by an enzyme called isomerase. Proteins, bearing C-terminus amino acids sequences His-Asp-Glu-Leu (HDEL) sequence yeast, (ER), which a eukaryotic cellular organelle involved synthesis, processing, transport, have considered to recycle between ER Golgi apparatus. The proposal this recycling model derives from study HDEL-tagged fusion protein. Here, localization oligosaccharide modification isomerase were investigated showed first direct evidence intrinsic transports Golgi. Results suggest native also accessible post-ER enzymes, yet accumulates ER.