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.
Highlights
A commonly used microorganism in biotechnology is Escherichia coli
Blocked in sec18 mutant, and newly synthesized proteins cannot leave the endoplasmic reticulum (ER) [14, 15]. These results suggested that the luminal ER protein, Protein disulfide isomerase (PDI), had reached the early Golgi compartment and received α-1,6 mannose addition
The results in this research study proposed the first direct evidence using a native protein in yeast that a luminal ER protein, PDI, transports from the ER to the Golgi compartment, and strongly supported the recycling model of the luminal ER protein that Pelham H.R. et al have proposed
Summary
A commonly used microorganism in biotechnology is Escherichia coli. This versatility is because of its fully sequenced genomic gene. Prokaryote is an easy-to-culture for expressing recombinant genes. In prokaryote cells, post-translational modification of proteins is significantly different compared to eukaryotes, or missing. In eukaryotes, newly synthesized polypeptide should be folded in the endoplasmic reticulum to form the unique conformation, but Escherichia coli does not have such a mechanism
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
