Interaction of plant mitochondrial and chloroplast signal peptides with the Hsp70 molecular chaperone.
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.
Zhang
Xiao-Ping
XP
Dept Biochemistry and Biophysics, Arrhenius Laboratories of Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden.
Glaser
Elzbieta
E
D000595:Amino Acid Sequence; D001692:Biological Transport; D002736:Chloroplasts / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D018832:Molecular Chaperones / Q000502:physiology*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D021382:Protein Sorting Signals; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013379:Substrate Specificity
D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; D021382:Protein Sorting Signals