Control of mitochondrial protein import by pH.
Protein import into mitochondria is inhibited by protons (IC(50) pH 6.5). The channels of the import machinery were examined to further investigate this pH dependence. TOM and TIM23 are the protein translocation channels of the mitochondrial outer and inner membranes, respectively, and their single channel behaviors at various pHs were determined using patch-clamp techniques. While not identical, increasing H(+) concentration decreases the open probability of both TIM23 and TOM channels. The pattern of the pH dependences of protein import and channel properties suggests TIM23 open probability can limit import of nuclear-encoded proteins into the matrix of yeast mitochondria.
Grigoriev
Sergey M
SM
Division of Basic Sciences, New York University College of Dentistry, New York, NY 10010, USA.
Jensen
Robert E
RE
Kinnally
Kathleen W
KW
D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D018408:Patch-Clamp Techniques; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
D002352:Carrier Proteins; D026901:Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D029701:Saccharomyces cerevisiae Proteins; C083081:TIM23 protein, S cerevisiae