Cytosolic factors in mitochondrial protein import.
In vitro import studies have confirmed the participation of cytosolic protein factors in the import of various precursor proteins into mitochondria. The requirement for extramitochondrial adenosine triphosphate for the import of a group of precursor proteins seems to be correlated with the chaperone activity of the cytosolic protein factors. One of the cytosolic protein factors is hsp70, which generally recognizes and binds unfolded proteins in the cytoplasm. Hsp70 keeps the newly synthesized mitochondrial precursor proteins in import-competent unfolded conformations. Another cytosolic protein factor that has been characterized is mitochondrial import stimulation factor (MSF), which seems to be specific to mitochondrial precursor proteins. MSF recognizes the mitochondrial precursor proteins, forms a complex with them and targets them to the receptors on the outer surface of mitochondria.
Mihara
K
K
Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan. mihara@cell.med.kyushu-u.ac.jp
Omura
T
T
D048948:14-3-3 Proteins; D001692:Biological Transport; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D008954:Models, Biological; D018832:Molecular Chaperones / Q000494:pharmacology; D011487:Protein Conformation; D011506:Proteins / Q000378:metabolism; D012156:Reticulocytes / Q000737:chemistry; D000099221:Protein Kinase C zeta
D048948:14-3-3 Proteins; D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D011506:Proteins; C490392:Prkcz protein, rat; D000099221:Protein Kinase C zeta; C490391:Ywhaz protein, rat; C090759:mitochondrial import stimulation factor, rat