mitochondrial import inner membrane translocase subunit TIM13 (TIMM13, TIM13B, TIMM13A, TIMM13B)

Function

• mitochondrial intermembrane chaperone
• import & insertion multiple transmembrane proteins into the mitochondrial inner membrane
• also required for transfer of beta-barrel precursors from the TOM complex to the sorting & assembly machinery (SAM complex) of the outer mitochondrial membrane
• acts as a chaperone-like protein that protects the hydrophobic precursors from aggregation & guides them t hrough the mitochondrial intermembrane space
• the TIMM8-TIMM13 complex mediates the import of proteins such as TIMM23, SLC25A12/ARALAR1 & SLC25A13/ARALAR2, while the predominant TIMM9-TIMM10 70 kD complex mediates the import of much more proteins
• forms heterohexamer; composed of 3 copies of TIMM8 (TIMM8A or TIMM8B) & 3 copies of TIMM13, named soluble 70 kD complex
• associates with the TIM22 complex

Structure

• the twin CX3C motif contains 4 conserved Cys that form 2 disulfide bonds in the mitochondrial intermembrane space
• however, during the transit of TIMM13 from cytoplasm into mitochondrion, the Cys probably coordinate Zn+2, thus preventing folding & allowing its transfer across the mitochondrial outer membrane (putative)
• belongs to the small Tim family

Compartment

mitochondrial inner membrane, intermembrane side

Expression

• ubiquitous
• highest expression in heart, kidney, liver & skeletal muscle

More general terms

• protein subunit
• mitochondrial membrane protein

Component of

• mitochondrial import inner membrane translocase subunit (TIM, translocase of inner mitochondrial membrane, mitochondrial protein importer)

Database

• OMIM: https://mirror.omim.org/entry/607383
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:2651
• UniProt: http://www.uniprot.org/uniprot/Q9Y5L4.html