TIM23 mitochondrial import inner membrane translocase complex

GO:0005744 · Other · Multiprotein complex · Proposed

The protein transport machinery of the mitochondrial inner membrane that typically transports proteins that possess a matrix-targeting N-terminal presequence. The TIM23 complex contains three essential Tim proteins: Tim17 and Tim23 are thought to build a preprotein translocation channel while Tim44 interacts transiently with the matrix heat-shock protein Hsp70 to form an ATP-driven import motor. [GO:0005744]

Synonyms: Tim23 complex; mitochondrial inner membrane pre-sequence translocase complex; mitochondrial inner membrane presequence translocase complex; mitochondrial inner membrane translocase complex

Part of: mitochondrial inner membrane (GO:0005743)

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: Budding-yeast mitochondria contain TIM23 inner-membrane presequence translocases that act downstream of TOM during matrix import. [DOI:10.1016/j.cell.2009.08.005]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Budding-yeast model for the TIM23 presequence translocase and its coordination with TOM and PAM during mitochondrial matrix import. [DOI:10.1016/j.cell.2009.08.005]

Functions

protein import into mitochondrial matrix GO:0030150 — TIM23 mediates the inner-membrane translocation step for presequence-containing precursor proteins destined for the mitochondrial matrix.
- GO:0005744 GO:0005744 defines TIM23 as mitochondrial inner-membrane protein-transport machinery that typically transports proteins with matrix-targeting N-terminal presequences.
- GO:0030150 GO:0030150 denotes protein import into the mitochondrial matrix from the cytosol via TOM, TIM23 and PAM.
- DOI:10.1016/j.cell.2009.08.005 Chacinska et al. 2009 reviewed TOM entry and downstream TIM23-PAM presequence import into the mitochondrial matrix.

Mechanism graphs

TIM23 mediates the inner-membrane matrix-import step (FUNCTION)

After TOM import across the mitochondrial outer membrane, TIM23 acts in the inner membrane to translocate presequence-containing precursors during matrix import.

Subject	Predicate	Object	Evidence
TIM23 mitochondrial import inner membrane translocase complex	is part of	mitochondrial inner membrane	`GO:0005744` GO:0005744 places TIM23 protein-transport machinery in the mitochondrial inner membrane.
mitochondrial outer membrane translocase complex	hands presequence precursors to	TIM23 mitochondrial import inner membrane translocase complex	`DOI:10.1016/j.cell.2009.08.005` Chacinska et al. 2009 reviewed TIM23-PAM as the downstream inner-membrane and matrix machinery for TOM-imported presequence precursors.
TIM23 mitochondrial import inner membrane translocase complex	supports	protein import into mitochondrial matrix	`GO:0030150` GO:0030150 grounds the matrix-import pathway that passes through TOM, TIM23 and PAM. `DOI:10.1007/s00441-016-2486-7` Demishtein-Zohary and Azem 2017 reviewed the function of the TIM23 mitochondrial protein import complex.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral family groundings and TIM23/PAM boundary decisions before adding Tim or PAM rows. GO exactly grounds the TIM23 complex itself and names Tim17, Tim23 and transient Tim44/Hsp70 motor association in its definition, but this first record leaves Tim17, Tim23, Tim44, Tim50, Pam17 and PAM-motor factor rows unasserted until exact family groundings are separated from stable TIM23 versus transient PAM/import-motor membership.

Evidence

GO:0005744 Gene Ontology cellular-component term for the TIM23 mitochondrial import inner membrane translocase complex.
GO:0098800 Gene Ontology cellular-component parent term for inner mitochondrial membrane protein complexes.
GO:0005743 Gene Ontology cellular-component term for the mitochondrial inner membrane that contains TIM23.
GO:0005742 Gene Ontology cellular-component term for the upstream TOM complex that supplies presequence precursors to TIM23.
GO:0030150 Gene Ontology biological-process term for protein import into the mitochondrial matrix.
DOI:10.1016/j.cell.2009.08.005 Chacinska et al. 2009, 'Importing mitochondrial proteins: machineries and mechanisms', Cell.
DOI:10.1007/s00441-016-2486-7 Demishtein-Zohary and Azem 2017, 'The TIM23 mitochondrial protein import complex: function and dysfunction', Cell and Tissue Research.

Curation history

2026-09-18T17:00:32Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-18T17:01:30Z codex · EXPANDED_RECORD — Added GO synonymy, inner-mitochondrial-membrane protein-complex parentage, mitochondrial-inner-membrane parthood, Saccharomyces scope, matrix-import function evidence, a nonmechanistic TOM-to-TIM23 graph, and a TIM23/PAM subunit-boundary TODO.
2026-09-18T17:13:59Z codex · ADDRESS_REVIEW — Resolved #1171 by adding top-level GO:0005742 evidence for the TOM graph node, resolved #1172 by separating source-neutral family grounding from TIM23/PAM boundary decisions in the subunit TODO, and resolved #1173 by weakening the TIM23-to-matrix-import edge from mediates to supports.
2026-09-18T17:28:18Z codex · FIX_REVIEW_HISTORY — Resolved #1174 by correcting swapped #1172 and #1173 references in the prior ADDRESS_REVIEW curation-history entry.

Source: data/structures/other/tim23_mitochondrial_import_inner_membrane_translocase_complex.yaml