Isomerase, protein disulfide

An intensity increase of different protein spots identified as, e.g., cortactin (three different phosphorylated forms white arrows) and protein disulfide-isomerase (black arrow) could be detected after stimulation with thrombin in both the immunoblot and the autoradiogram. Several of the identified proteins were known to be involved in signal transduction and platelet function. 

PDI is a noncovalent homodimer with a molecular weight of 57 kDa for each subunit. The protein is generally involved in the formation, reduction and rearrangement of disulfide bridges and plays an important role in platelet function. PDI is localized at the extracellular side of the plasma membrane and is secreted after platelet activation (Chen etal, 1992). In platelets, PDI catalyzes the formation of disulfide-bridged complexes of thrombospondin 1 and thrombin-antithrombin III and is thus involved in hemostasis and wound healing (Milev and Essex, 1999). 

A Fragment ion spectrum of the nonphos-phorylated peptide LPSpSPVYEDAASFK of cortactin. 

B Fragment ion spectrum of the nonphos-phorylated peptide LPSSPVYEDAASFK of cortactin. Due to the secessions of-98 Da from y i Ser-418 (Ser-4 in the spectrum) was unambiguously detected to be phosphory-lated. 

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Disulfide bonds between and within polypeptides stabilize tertiary and quaternary structure. However, disulfide bond formation is nonspecific. Under oxidizing conditions, a given cysteine can form a disulfide bond with the —SH of any accessible cysteinyl residue. By catalyzing disulfide exchange, the rupture of an S— bond and its reformation with a different partner cysteine, protein disulfide isomerase facilitates the formation of disulfide bonds that stabilize their native conformation. 

Proteins that assist folding include protein disulfide isomerase, protine- V,rn2 j,-isomerase, and the chaperones that participate in the folding of over half of mammalian proteins. Chaperones shield newly synthesized polypeptides from solvent and provide an environment for elements of secondary stmcture to emerge and coalesce into molten globules. 

Ou W, Silver J. Role of protein disulfide isomerase and other thiol-reactive proteins in HIV-1 envelope protein-mediated fusion. Virology 2006 350(2) 406-417. 

Epe, C., Kohlmetz, C. and Schnieder, T. (1998) A recombinant protein disulfide isomerase homologue from Ancylostoma caninum. Parasitology Research 84, 763-766. 

Kivirikko, K.I. and Pihlajaniemi, T. (1998) Collagen hydroxylases and the protein disulfide isomerase subunit of prolyl 4-hydroxylases. Advances inEnzymology and Related Areas of Molecular Biology 72, 325-400. 

Schonbranner, E.R. and Schmid, F.X. (1992) Peptidyl-prolyl cis-trans isomerase improves the efficiency of protein disulfide isomerase as a catalyst of protein folding. Proceedings of the National Academy of Sciences USA 89, 4510-4513. 

Veijola, J., Koivunen, P., Annunen, P., Pihlajaniemi, T. and Kivirikko, K. (1994) Cloning, baculovirus expression, and characterization of the alpha-subunit of prolyl 4-hydroxylase from the nematode Caenorhabditis elegans - this alpha-subunit forms an active alpha-beta dimer with the human protein disulfide-isomerase beta-subunit. Journal of Biological Chemistry 269, 26746-26753. 

Vuori, K., Pihlajaniemi, T., Myllyla, R. and Kivirikko, K.I. (1992) Site-directed mutagenesis of human protein disulfide isomerase - effect on the assembly, activity and endoplasmic-reticulum retention of human prolyl 4-hydroxylase in Spodoptera frugiperda insect cells. EMBO JoumalW, 4213-4217. 

Wilson, R., Lees, J.F. and Bulleid, N.J. (1998) Protein disulfide isomerase acts as a molecular chaperone during the assembly of procollagen. Journal of Biological Chemistry 273, 9637-9643. 

Wilson, W.R., Tuan, R.S., Shepley, K.J., Freedman, D.O., Greene, B.M., Awadzi, K. and Unnasch, T.R. (1994) The Onchocerca volvulus homologue of the multifunctional polypeptide protein disulfide isomerase. Molecular and Biochemical Parasitology 68, 103-117. 

MTP is responsible for the transfer of TGs and cholesteryl esters from the endoplasmic reticulum (ER) to lipoprotein particles (VLDL in hepatocytes in the liver and chylomicrons in endocytes in the intestine) for secretion [52]. It is a heterodimer consisting of a unique large subunit essential for lipid transfer encoded by the mttp gene and a smaller subunit, the ubiquitous ER enzyme protein disulfide isomerase [53]. 

N203-dependent S-nitrosation has been demonstrated in the case of semm albumin (Nedospasov et al, 2000 Rafikova et al., 2002), in membranes (Liu et al., 1998) and in the protein-disulfide isomerase dependent transfer of NO-equivalents from extracellular RSNOs to the cytosol (Ramachandran et al., 2001). 

We and others have demonsttated that an endothelial, cell surface protein-disulfide isomerase-mediated mechanism, does exist for the rapid influx of RSNO bound-NO (Zai et al. 1999 Ramachandran et al., 2001). Whether the csPDI route plays a role in the transfer of NO-equivalents from RBCs remains to be answered. 

Burgess, ). K., FIotchkiss, K. A., Suter, C., Dudman, N. P., Szollosi, J., Chesterman, C. N., Chong, B. H., Hogg, P. J., Physical proximity and functional association of glycoprotein lbalpha and protein-disulfide isomerase on the platelet plasma membrane,/. Biol. Chem. 275 (2000), p.9758-9766... 

Essex, D. W., Chen, K., Swiatkowska, M., Localization of protein disulfide isomerase to the external surface of the platelet plasma membrane, Blood. 86 (1995), p. 2168-2173... 

Essex, D. W., Li, M., Miller, A., Feinman, R. D., Protein disulfide isomerase and sulfhydryl-dependent pathways in platelet activation, Biochemistry (2001), p. 6070-6075... 

Lahav, J., Gofer-Dadosh, N., Luboshitz, J., Hess, O., Shaklai, M., Protein disulfide isomerase mediates integrin-dependent adhesion, FEES Lett. 475 (2000), p. 89-92... 

Noiva, R., Lennarz, W. J., Protein disulfide isomerase. A multifunctional protein resident in the lumen of the endoplasmic reticulum, /. Biol. Chem. 267 (1992),... 

Ramachandran, N., Root, P., Jiang, X. M., Hogg, P. J., Mutus, B., Mechanism of transfer of NO from extracellular S-nitrosothiols into the cytosol by cell-surface protein disulfide isomerase, Proc. Natl. Acad. Sci. USA 98 (2001), p.9539-9544... 

Raturi, A., Mutus, B., Use of 2,3-diaminonapthalene for studying denitrosation activity of protein disulfide isomerase, Anal Biochem. 

Zai, A., Rudd, M. A., Scribner, A. W., Loscalzo, J., Cell-surface protein disulfide isomerase catalyzes transnitrosation and regulates intracellular transfer of nitric oxide, J. Clin. Invest. 103 (1999), p. 393-399... 

Disulfides can be reduced to two thiols (Fig. 5.14). The best example is the reduction of oxidized glutathione (GSSG) back to the reduced form (GSH) (Fig. 5.14), which is mediated by glutathione reductase. In addition, exchange can occur with other thiols mediated by protein disulfide isomerase. In principle, sulfenic acids can probably also be reduced back to thiols, but because of the reactivity of the sulfenic acid, this is not generally observed. 

The hbraries of enzyme substrates were obtained by spht-pool synthesis to yield one-bead-one-compound hbraries. The substrate assay was performed with a range of proteolytic enzymes such as subtilisin Carlsberg [26], cruzipain [27], protein disulfide isomerase [28-29], matrix metalloprotease MM P-9 [30], papain [31],... 

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