Editing Disulfide (section)

====In eukaryotes====
In [[eukaryote|eukaryotic]] cells, in general, stable disulfide bonds are formed in the lumen of the [[rough endoplasmic reticulum|RER]] (rough endoplasmic reticulum) and the [[mitochondrial intermembrane space]] but not in the [[cytosol]]. This is due to the more oxidizing environment of the aforementioned compartments and more reducing environment of the cytosol (see [[glutathione]]). Thus disulfide bonds are mostly found in secretory proteins, lysosomal proteins, and the exoplasmic domains of membrane proteins.

There are notable exceptions to this rule. For example, many nuclear and cytosolic proteins can become disulfide-crosslinked during necrotic cell death.<ref>{{Cite journal |last1=Samson |first1=Andre L. |last2=Knaupp |first2=Anja S. |last3=Sashindranath |first3=Maithili |last4=Borg |first4=Rachael J. |last5=Au |first5=Amanda E.-L. |last6=Cops |first6=Elisa J. |last7=Saunders |first7=Helen M. |last8=Cody |first8=Stephen H. |last9=McLean |first9=Catriona A. |date=2012-10-25 |title=Nucleocytoplasmic coagulation: an injury-induced aggregation event that disulfide crosslinks proteins and facilitates their removal by plasmin |journal=[[Cell Reports]] |volume=2 |issue=4 |pages=889–901 |doi=10.1016/j.celrep.2012.08.026 |issn=2211-1247 |pmid=23041318 |doi-access=free}}</ref> Similarly, a number of cytosolic proteins which have cysteine residues in proximity to each other that function as oxidation sensors or [[redox]] catalysts; when the reductive potential of the cell fails, they oxidize and trigger cellular response mechanisms. The virus ''[[Vaccinia]]'' also produces cytosolic proteins and peptides that have many disulfide bonds; although the reason for this is unknown presumably they have protective effects against intracellular proteolysis machinery.

Disulfide bonds are also formed within and between [[protamine]]s in the [[sperm]] [[chromatin]] of many [[mammal]]ian species.