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Trends Plant Sci. 2002 Jan;7(1):14-21.

Interaction of plant mitochondrial and chloroplast signal peptides with the Hsp70 molecular chaperone.

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Dept Biochemistry and Biophysics, Arrhenius Laboratories of Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden.


Most mitochondrial and chloroplast proteins are synthesized on cytosolic polyribosomes as precursor proteins, with an N-terminal signal sequence that targets the precursor to the correct organelle. In mitochondria, the chaperone Hsp70 functions as a molecular motor, pulling the precursor across the mitochondrial membranes; 97.0% of plant mitochondrial presequences contain an Hsp70 binding site. In chloroplasts, the outer envelope, intermembrane space and a stromal Hsp70 are thought to participate in protein import; 82.5% of chloroplast transit peptides have an Hsp70 binding site. The interaction of signal peptides with Hsp70 during the import process is supported by biochemical and bioinformatic studies.

[Indexed for MEDLINE]

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