title: Crosstalk and barriers between the electron carriers of the endoplasmic reticulum.
abstract: CONCLUSIONS
  The lumen of the endoplasmic reticulum (ER) constitutes a separate compartment with a special proteome and metabolome. The characteristic redox environment required for the optimal functioning of local pathways is defined by the redox couples of the main electron carriers. These molecules, glutathione, pyridine nucleotides, and ascorbic acid, are present within the ER, but their composition, concentration, and redox state are characteristically different from those observed in other subcellular compartments. Spatial and kinetic barriers contribute to the generation and maintenance of this special redox environment.
  
  
  BACKGROUND
  The ER redox has usually been considered from the perspective of oxidative protein folding, one of the major functions of the ER. Thus, the lumen has been described as a relatively oxidizing subcellular compartment.
  
  
  RESULTS
  The ER redoxome has been scantily mapped. However, recent observations suggest that the redox systems in reduced and oxidized states are present simultaneously. The concerted actions of transmembrane uptake processes and local oxidoreductases as well as the absence of specific transport and enzyme activities maintain the oxidized state of the thiol-disulfide systems and the reduced state of the pyridine nucleotide redox systems. These states are prerequisites for the normal redox reactions localized in the ER.
  
  
  CONCLUSIONS
  An outline of the interactions between the major electron carriers of the ER will contribute to a better understanding of human diseases related to ER redox homeostasis.
authors.affiliation: Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary. banhegyi@eok.sote.hu
authors.forename: Gábor
authors.initials: G
authors.lastname: Bánhegyi
authors.forename: Eva
authors.initials: E
authors.lastname: Margittai
authors.forename: András
authors.initials: A
authors.lastname: Szarka
authors.forename: József
authors.initials: J
authors.lastname: Mandl
authors.forename: Miklós
authors.initials: M
authors.lastname: Csala
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism; D004579:Electron Transport; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D059865:Endoplasmic Reticulum Stress; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000227:Adenine Nucleotides; D017382:Reactive Oxygen Species; D005978:Glutathione; D001205:Ascorbic Acid