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Cloning and characterization of chloroplast and cytosolic forms of cyclophilin from Arabidopsis thaliana
Cyclophilin (CyP), a protein with peptidyl-prolyl cis-trans isomerase (rotamase) activity, is the specific cellular target of cyclosporin A. We have isolated cDNA clones of two genes (designated ROC1 and ROC4) encoding CyP homologs from Arabidopsis thaliana (L.). The protein products of these genes...
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Published in: | The Journal of biological chemistry 1994-03, Vol.269 (11), p.7863-7868 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Cyclophilin (CyP), a protein with peptidyl-prolyl cis-trans isomerase (rotamase) activity, is the specific cellular target
of cyclosporin A. We have isolated cDNA clones of two genes (designated ROC1 and ROC4) encoding CyP homologs from Arabidopsis
thaliana (L.). The protein products of these genes are distinct from a previously identified Arabidopsis CyP. ROC1 is expressed
in all tested plant organs and encodes a protein which is highly similar to previously described cytosolic CyP isoforms of
other plants. In contrast, ROC4 is expressed only in photosynthetic organs and encodes a protein which includes an amino-terminal
extension with properties of known chloroplast transit peptides. In vitro import experiments using the putative precursor
protein to ROC4 showed that the protein is imported into chloroplasts where it is processed to the predicted mature size.
Rotamase assays and immunoblot analysis of subcellular fractions indicate the presence of a CyP isoform in the stroma of chloroplasts
but not in the thylakoid membranes or thylakoid lumen. Together, these data show that ROC4 is a novel CyP isoform which is
located in the stroma of chloroplasts. In vitro chloroplast import of precursors of other chloroplast proteins was unaffected
by concentrations of cyclosporin A which completely inhibit rotamase activity of chloroplast stromal CyP. Thus, this activity
is not essential for protein import into chloroplasts. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(17)37130-2 |