Activating Compound | Comment | Organism | Structure |
---|---|---|---|
additional information | the soluble co-chaperone Mge1 stimulates ADP/ATP exchange | Saccharomyces cerevisiae |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
mitochondrion | - |
Saccharomyces cerevisiae | 5739 | - |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
ATP + H2O | Saccharomyces cerevisiae | - |
ADP + phosphate | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Saccharomyces cerevisiae | - |
- |
- |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
ATP + H2O | - |
Saccharomyces cerevisiae | ADP + phosphate | - |
? | |
additional information | the active presequence translocase drives motor-dependent mitochondrial protein translocation | Saccharomyces cerevisiae | ? | - |
? |
Synonyms | Comment | Organism |
---|---|---|
mitochondrial hsp70 | - |
Saccharomyces cerevisiae |
mtHSP70 | - |
Saccharomyces cerevisiae |
General Information | Comment | Organism |
---|---|---|
malfunction | temperature-sensitive mutants of mitochondrial Hsp70, affected in either ATP-binding and hydrolysis or Tim44 interaction, display defects in matrix protein import and concomitant TOM/TIM23-supercomplex formation when import reactions were performed under non-permissive conditions | Saccharomyces cerevisiae |
physiological function | in mitochondria, matrix translocation of polypeptides depends on the ATP-powered mitochondrial Hsp70 (mtHsp70), the catalytic constituent of the presequence translocase-associated motor (PAM), at the trans side of the protein-conducting channel. mtHsp70 exists in a soluble pool mediating matrix protein folding and a TIM23-associated pool generating precursor velocity over the inner membrane. During precursor transport, a translocation intermediate is established in which the motor-associated, unfolded precursor simultaneously spans the TOM and TIM23 complexes thereby generating a mitochondrial contact site. For both activities, the soluble co-chaperone Mge1 stimulates ADP/ATP exchange. To drive precursor translocation, the Hsp70-import motor associates with the protein-conducting channel of the TIM23 complex, the ATPase cycle of Hsp70 is regulated in the context of a translocating polypeptide chain. The presence of all Hsp70 co-chaperones at the import channel is not sufficient to promote matrix protein import, instead a recharging of the active translocase with Pam18 is required for motor activity. Thus, a replenishment cycle of co-chaperones at the TIM23 complex is an integral part of Hsp70s ATPase cycle at the channel exit site and essential to maintain motor-driven mitochondrial protein import. The association of the membrane-bound co-chaperones with the Tim23 channel unit is a prerequisite for the spatially controlled mtHsp70 regulation in mitochondria. Pam18 needs to be recharged at the translocase in order to maintain progressive mtHsp70 activity, such a replenishment cycle of the translocases co-chaperone Pam18 drives the ATP hydrolysis of the import motor in the precursor-occupied translocase and thus precursor transport along the presequence pathway, overview | Saccharomyces cerevisiae |