Protein disulfide isomerase appears necessary to maintain the catalytically active structure of the microsomal triglyceride transfer protein.

Protein disulfide isomerase (PDI) is a component of the microsomal triglyceride transfer protein (MTP) complex. This study was initiated to help elucidate the role of PDI in MTP. The 88-kDa polypeptide of MTP (88K) was dissociated from PDI by using chaotropic agents (NaClO4 and KSCN), low concentrations of a denaturant (guanidine hydrochloride) or a nondenaturing detergent (octyl glucoside). As assessed by fluorescence and circular dichroism spectroscopy, these three different approaches appeared to dissociate the components of MTP under mild, nondenaturing conditions. The dissociating agents were diluted or removed by dialysis, and the free PDI and 88K were further characterized. In all cases, the dissociation coincided with the loss of triglyceride transfer activity. The free 88-kDa polypeptide readily aggregated, suggesting that it is a hydrophobic peptide. Even in the presence of chaotropic agents, when 88K was not aggregated, transfer activity was not expressed. These results suggest that the association of PDI with 88K is necessary to maintain the catalytically active form of the triglyceride transfer protein and prevent the aggregation of 88K.

[1]  L. Aggerbeck,et al.  Structural properties of the microsomal triglyceride-transfer protein complex. , 1991, Biochemistry.

[2]  T. Shibata,et al.  A subunit of yeast site-specific endonuclease SceI is a mitochondrial version of the 70-kDa heat shock protein. , 1990, The Journal of biological chemistry.

[3]  N.,et al.  Protein disulfide isomerase is a component of the microsomal triglyceride transfer protein complex. , 1990, The Journal of biological chemistry.

[4]  J. Rothman.  Polypeptide chain binding proteins: Catalysts of protein folding and related processes in cells , 1989, Cell.

[5]  R. Freedman.  Protein disulfide isomerase: Multiple roles in the modification of nascent secretory proteins , 1989, Cell.

[6]  L. McLean,et al.  Effect of probucol on the physical properties of low-density lipoproteins oxidized by copper. , 1989, Biochemistry.

[7]  K. Kivirikko,et al.  Prolyl 4-hydroxylase from Volvox carteri. A low-Mr enzyme antigenically related to the alpha subunit of the vertebrate enzyme. , 1988, The Biochemical journal.

[8]  R. Freedman,et al.  Defective co-translational formation of disulphide bonds in protein disulphide-isomerase-deficient microsomes , 1988, Nature.

[9]  K. Tasanen,et al.  A single polypeptide acts both as the beta subunit of prolyl 4-hydroxylase and as a protein disulfide-isomerase. , 1987, The Journal of biological chemistry.

[10]  B. Wallace,et al.  Differential absorption flattening optical effects are significant in the circular dichroism spectra of large membrane fragments. , 1987, Biochemistry.

[11]  G. M. Helmkamp,et al.  Phospholipid transfer proteins: Mechanism of action , 1986, Journal of bioenergetics and biomembranes.

[12]  D. B. Zilversmit,et al.  Localization of intracellular triacylglycerol and cholesteryl ester transfer activity in rat tissues. , 1986, Biochimica et biophysica acta.

[13]  J T Yang,et al.  Calculation of protein conformation from circular dichroism. , 1986, Methods in enzymology.

[14]  D. B. Zilversmit,et al.  Purification and characterization of microsomal triglyceride and cholesteryl ester transfer protein from bovine liver microsomes. , 1985, Chemistry and physics of lipids.

[15]  D. B. Zilversmit,et al.  A triglyceride and cholesteryl ester transfer protein associated with liver microsomes. , 1984, The Journal of biological chemistry.

[16]  R. Freedman,et al.  Formation and isomerization of disulfide bonds in proteins: protein disulfide-isomerase. , 1984, Methods in enzymology.

[17]  H. K. Schachman,et al.  Assembly of the catalytic trimers of aspartate transcarbamoylase from folded monomers. , 1982, The Journal of biological chemistry.

[18]  J. B. Massey,et al.  Kinetics of spontaneous and plasma-stimulated sphingomyelin transfer. , 1982, Biochimica et biophysica acta.

[19]  T. E. Thompson,et al.  Glucocerebroside transfer between phosphatidylcholine bilayers. , 1982, Biochemistry.

[20]  W. Kao,et al.  The assembly of tetrameric prolyl hydroxylase in tendon fibroblasts from newly synthesized alpha-subunits and from preformed cross-reacting protein. , 1980, The Biochemical journal.

[21]  T. E. Thompson,et al.  Mechanism of the spontaneous transfer of phospholipids between bilayers. , 1980, Biochemistry.

[22]  S. Chen‐Kiang,et al.  Homology between a prolyl hydroxylase subunit and a tissue protein that crossreacts immunologically with the enzyme. , 1977, Proceedings of the National Academy of Sciences of the United States of America.

[23]  K. Kivirikko,et al.  Tetramers and monomers of prolyl hydroxylase in isolated chick-embryo tendon cells. The association of inactive monomers to active tetramers and a preliminary characterization of the intracellular monomer-size protein. , 1977, European journal of biochemistry.

[24]  D. Livingston.  Immunoaffinity chromatography of proteins. , 1974, Methods in enzymology.

[25]  W. Hunter,et al.  The labelling of proteins to high specific radioactivities by conjugation to a 125I-containing acylating agent. , 1973, The Biochemical journal.

[26]  D. Prockop,et al.  Affinity column purification of protocollagen proline hydroxylase from chick embryos and further characterization of the enzyme. , 1973, The Journal of biological chemistry.

[27]  U. K. Laemmli,et al.  Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4 , 1970, Nature.

[28]  F. Delorenzo,et al.  Enzymically catalyzed disulfide interchange in randomly cross-linked soybean trypsin inhibitor. , 1965 .

[29]  B. Davis.  DISC ELECTROPHORESIS – II METHOD AND APPLICATION TO HUMAN SERUM PROTEINS * , 1964, Annals of the New York Academy of Sciences.

[30]  C. Epstein,et al.  PURIFICATION AND PROPERTIES OF A MICROSOMAL ENZYME SYSTEM CATALYZING THE REACTIVATION OF REDUCED RIBONUCLEASE AND LYSOZYME. , 1964, The Journal of biological chemistry.

[31]  C. Epstein,et al.  Acceleration of reactivation of reduced bovine pancreatic ribonuclease by a microsomal system from rat liver. , 1963, The Journal of biological chemistry.

[32]  O. H. Lowry,et al.  Protein measurement with the Folin phenol reagent. , 1951, The Journal of biological chemistry.