TITLE:
Evidence That Protein Disulfide Isomerase in Yeast Saccharomyces cerevisiae Is Transported from the ER to the Golgi Apparatus
AUTHORS:
Tadashi Miura, Yukari Oda, Yasuhiko Shizawa
KEYWORDS:
Protein Disulfide Isomerase, Endoplasmic Reticulum, Golgi Apparatus, Oligosaccharide Modification, Protein Localization
JOURNAL NAME:
Journal of Biomedical Science and Engineering,
Vol.15 No.2,
February
14,
2022
ABSTRACT: Newly synthesized membrane and secretory proteins in cells undergo folding in the endoplasmic reticulum with the introduction of disulfide bonds and acquire the correct three-dimensional structure. Disulfide bonds are especially important for protein folding. It has been thought that formation of protein disulfide bonds in eukaryotes is mainly carried out by an enzyme called protein disulfide isomerase. Proteins, bearing the C-terminus of amino acids sequences with His-Asp-Glu-Leu (HDEL) sequence in yeast, in the endoplasmic reticulum (ER), which is a eukaryotic cellular organelle involved in protein synthesis, processing, and transport, have been considered to recycle between ER and Golgi apparatus. The proposal for this recycling model derives from the study of an HDEL-tagged fusion protein. Here, the localization and oligosaccharide modification of protein disulfide isomerase were investigated in yeast, and showed the first direct evidence that this intrinsic ER protein transports from ER to Golgi. Results suggest that this native protein is also accessible to post-ER enzymes, and yet accumulates in the ER.