Recombinant Schizosaccharomyces pombe Presequence translocated-associated motor subunit pam17, mitochondrial (pam17)
Description
Overview of Pam17 Function
Pam17 is a component of the PAM complex, which drives the import of preproteins into mitochondria . The mitochondrial heat shock protein 70 (mtHsp70) is the central component of PAM, generating an import driving activity that is ATP-dependent . Pam17 influences the association of Pam18 and Pam16 in the J-complex, which are also regulatory subunits of the PAM complex .
Interaction with the TIM23 Complex
Pam17 interacts with the Tim23 channel protein, indicating a binding site between the TIM23 complex and Pam17 . The TIM23 complex mediates the import of preproteins across the mitochondrial inner membrane . Tim44, another component, was initially thought to be a scaffold for binding motor subunits, but it plays a differential role in recruiting PAM modules to the inner membrane translocase .
Role of Tim44
Tim44 is an adaptor protein that binds mtHsp70 and links it to the TIM23 complex . Studies using a tim44-804 mutant have shown that Tim44 inactivation leads to a reorganization within the TIM23-PAM machinery . The J-complex dissociates from the translocase, while Pam17 binding to Tim23 is enhanced . This suggests Tim44 has a critical function in the dynamics of the mitochondrial import motor .
Pam17 in Saccharomyces cerevisiae
While Pam17 is conserved, its precise localization and role are unclear . It was identified as a component of the import motor in Saccharomyces cerevisiae .
Involvement in Mitochondrial Quality Control
Pam17 is required for the translocation activity and architecture of the mitochondrial protein import motor . It is also involved in quality control pathways of mitochondria . Deletion of PAM17 in the rsp5-1 yeast mutant results in a synthetic growth defect and accumulation of the Mdj1 precursor, indicating that Rsp5 has a role in the removal of non-imported preproteins .
Post-translational Roles
Homologs of Cbp3, Cbp6, and Mss51 in S. pombe function at post-translational steps of respiratory complex biogenesis, contrasting with their roles in Saccharomyces cerevisiae . These proteins are involved in the assembly of respiratory complexes III and IV .
Experimental Evidence
Studies on tim44-804 mutants show a selective import defect for precursors destined for the mitochondrial matrix . Inactivation of Tim44 leads to a reorganization within the TIM23-PAM machinery, enhancing Pam17 binding to Tim23 .
Table: Key Interactions and Functions of Pam17
| Protein/Complex | Interaction | Function |
|---|---|---|
| mtHsp70 | Part of PAM complex | Drives import of preproteins |
| Tim23 | Direct binding | Part of protein import channel |
| Tim44 | Indirect, through PAM complex | Dynamics of mitochondrial import motor |
| Pam18/Pam16 (J-complex) | Influences association | Regulation of mtHsp70 activity |
Product Specs
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Target Background
KEGG: spo:SPAC167.04
STRING: 4896.SPAC167.04.1
