A J-Protein Is an Essential Subunit of the Presequence Translocase-Associated Protein Import Motor of Mitochondria

• Published in: The Journal of cell biology 2003-11, Vol.163 (4), p.707-713
• Main Authors: Truscott, Kaye N., Voos, Wolfgang, Frazier, Ann E., Lind, Maria, Li, Yanfeng, Geissler, Andreas, Dudek, Jan, Müller, Hanne, Sickmann, Albert, Meyer, Helmut E., Meisinger, Chris, Guiard, Bernard, Rehling, Peter, Pfanner, Nikolaus
• Format: Article
• Language: English
• Subjects: Adenosine triphosphatases; Amino Acid Sequence - genetics; Antibodies; Base Sequence - genetics; Carrier Proteins - metabolism; Cell cycle; Cells, Cultured; Cellular biology; DNA, Complementary - analysis; DNA, Complementary - genetics; Heat-Shock Proteins - metabolism; HSP70 Heat-Shock Proteins - metabolism; Imports; J-protein; Macromolecular Substances; Membrane proteins; Membrane Proteins - genetics; Membrane Proteins - isolation & purification; Membrane Proteins - metabolism; Membrane Transport Proteins - genetics; Membrane Transport Proteins - isolation & purification; Membrane Transport Proteins - metabolism; Mge1 protein; Mitochondria; Mitochondria - metabolism; Mitochondrial DNA; Mitochondrial Membrane Transport Proteins; Molecular Chaperones; Molecular Motor Proteins - metabolism; Molecular Sequence Data; P branes; Protein precursors; Protein transport; Protein Transport - physiology; Proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - isolation & purification; Saccharomyces cerevisiae Proteins - metabolism; Tim44 protein; Western blotting; Yeasts
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.200308004

Transport of preproteins into the mitochondrial matrix is mediated by the presequence translocase-associated motor (PAM). Three essential subunits of the motor are known: mitochondrial Hsp70 (mtHsp70); the peripheral membrane protein Tim44; and the nucleotide exchange factor Mge1. We have identified the fourth essential subunit of the PAM, an essential inner membrane protein of 18 kD with a J-domain that stimulates the ATPase activity of mtHsp70. The novel J-protein (encoded by PAM18/YLR008c/TIM14) is required for the interaction of mtHsp70 with Tim44 and protein translocation into the matrix. We conclude that the reaction cycle of the PAM of mitochondria involves an essential J-protein.