Proteins of the PDI family: unpredicted non-ER locations and functions.
Protein disulfide isomerases (PDIs) constitute a family of structurally related enzymes which catalyze disulfide bonds formation, reduction, or isomerization of newly synthesized proteins in the lumen of the endoplasmic reticulum (ER). They act also as chaperones, and are, therefore, part of a quality-control system for the correct folding of the proteins in the same subcellular compartment. While their functions in the ER have been thoroughly studied, much less is known about their roles in non-ER locations, where, however, they have been shown to be involved in important biological processes. At least three proteins of this family from higher vertebrates have been found in unusual locations (i.e., the cell surface, the extracellular space, the cytosol, and the nucleus), reached through an export mechanism which has not yet been understood. In some cases their function in the non-ER location is clearly related to their redox properties, but in most cases their mechanism of action has still to be disclosed, although their propensity to associate with other proteins or even with DNA might be the main factor responsible for their activities.
Turano
Carlo
C
Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche 'Alessandro Rossi-Fanelli' and Centro di Biologia Molecolare del CNR, Università 'La Sapienza', Rome, Italy. cturano@uniroma1.it
Coppari
Sabina
S
Altieri
Fabio
F
Ferraro
Anna
A
D000818:Animals; D002462:Cell Membrane / Q000201:enzymology*; D002467:Cell Nucleus / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology*; D004721:Endoplasmic Reticulum / Q000201:enzymology; D005110:Extracellular Space / Q000201:enzymology; D006801:Humans; D010084:Oxidation-Reduction; D019704:Protein Disulfide-Isomerases / Q000737:chemistry / Q000502:physiology*; D017434:Protein Structure, Tertiary
D019704:Protein Disulfide-Isomerases