Peptidyl prolyl cis-trans-isomerase activity associated with the lumen of the endoplasmic reticulum.
Peptidyl prolyl cis-trans-isomerase (PPI) activity was detected in microsomal fractions from bovine and rat liver. Extensive washing, proteinase and sonication treatments indicated that although some of this activity was due to adsorbed cytosolic enzymes, there was also an active but latent microsomal PPI activity. Density-gradient subfractionation indicated that activity was associated with vesicles derived from both the rough and the smooth endoplasmic reticulum (ER), suggesting that the activity was located within the ER lumen. The luminal PPI activity was inhibited by cyclosporin A and was active towards an unfolded protein substrate as well as towards the standard peptide substrate.
Bose
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Research School of Biosciences, Biological Laboratory, University of Kent, Canterbury, U.K.
Freedman
R B
RB
D000591:Amino Acid Isomerases / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002417:Cattle; D002451:Cell Compartmentation; D016572:Cyclosporine / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D008862:Microsomes, Liver / Q000201:enzymology*; D019696:Peptidylprolyl Isomerase; D051381:Rats; D006163:Ribonuclease T1 / Q000494:pharmacology
D002352:Carrier Proteins; D016572:Cyclosporine; D006163:Ribonuclease T1; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase