TIMM23 PAM translocates proteins from the mitochondrial intermembrane space to the mitochondrial matrix

Stable Identifier
Reaction [transition]
Homo sapiens
Locations in the PathwayBrowser
SVG |   | PPTX  | SBGN
Click the image above or here to open this reaction in the Pathway Browser
The layout of this reaction may differ from that in the pathway view due to the constraints in pathway layout

As inferred from the yeast TIM23 complex, the human TIMM23 complex transports precursor proteins across the inner membrane and into the matrix. As in yeast, subunits TIMM50, TIMM17, and TIMM23 are probably necessary for initiating translocation while the PAM complex with mtHSP70 (HSPA9, yeast SSC1) provides the motive force that drives the transport. mtHSP70 binding to the precursor pulls the protein into the matrix in a reaction requiring ATP hydrolysis. The yeast reaction appears to use a Brownian ratchet mechanism (Yamano et al. 2008).
In yeast experimentally verified substrates of TIM23 PAM include Hsp60 (HSP60 in human) and Yfh1 (Frataxin, FXN in human). Many other matrix proteins are believed to be substrates of the TIMM23 complex

Literature References
PubMed ID Title Journal Year
19453276 Multiple pathways for mitochondrial protein traffic

Yamano, K, Endo, T

Biol Chem 2009
18174896 Multiple pathways for sorting mitochondrial precursor proteins

Pfanner, N, Wagner, R, Sickmann, A, Bolender, N, Meisinger, C

EMBO Rep 2008
18678864 Step-size analyses of the mitochondrial Hsp70 import motor reveal the Brownian ratchet in operation

Esaki, M, Yamano, K, Yokota, M, Endo, T, Kuroyanagi-Hasegawa, M

J Biol Chem 2008
Catalyst Activity

protein transmembrane transporter activity of TIMM23 PAM:Cargo [mitochondrial inner membrane]

Inferred From
Cite Us!