Holo-translocon SecYEG-SecDF-YajC-YidC complex

cellstructuremech:holo_translocon_secyeg_secdf_yajc_yidc_complex · Secretion system · Multiprotein complex · Proposed

An Escherichia coli Sec-pathway plasma-membrane holo-translocon complex in which SecY, SecE, SecG, SecD, SecF, YajC, and YidC assemble as a heteroheptamer that supports protein secretion and membrane-protein insertion. [ComplexPortal:CPX-1095]

Synonyms: HTL complex

Has part: SecYEG translocon complex (cellstructuremech:secyeg_translocon_complex)

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

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
Protein translocase subunit SecY	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	secY	1 copy in the E. coli K-12 Complex Portal CPX-1095 entry	UNKNOWN	Core protein-conducting channel subunit that forms the central pore and lateral gate used during secretion and membrane-protein insertion. `ComplexPortal:CPX-1095` Complex Portal CPX-1095 curates UniProtKB:P0AGA2/secY as a one-copy participant in the E. coli K-12 SecYEG-SecDF-YajC-YidC holo-translocon. `PMID:27435098` Komar et al. 2016 describe the bacterial holo-translocon as a SecYEG-SecDF-YajC-YidC supercomplex in the E. coli inner membrane.
Protein translocase subunit SecE	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	secE	1 copy in the E. coli K-12 Complex Portal CPX-1095 entry	UNKNOWN	Core channel constituent that braces SecY in the SecYEG module of the holo-translocon. `ComplexPortal:CPX-1095` Complex Portal CPX-1095 curates UniProtKB:P0AG96/secE as a one-copy participant in the E. coli K-12 SecYEG-SecDF-YajC-YidC holo-translocon. `PMID:27435098` Komar et al. 2016 describe the bacterial holo-translocon as a SecYEG-SecDF-YajC-YidC supercomplex in the E. coli inner membrane.
Protein-export membrane protein SecG	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	secG	1 copy in the E. coli K-12 Complex Portal CPX-1095 entry	UNKNOWN	SecYEG channel constituent that completes the SecYEG module inside the larger holo-translocon. `ComplexPortal:CPX-1095` Complex Portal CPX-1095 curates UniProtKB:P0AG99/secG as a one-copy participant in the E. coli K-12 SecYEG-SecDF-YajC-YidC holo-translocon. `PMID:27435098` Komar et al. 2016 describe the bacterial holo-translocon as a SecYEG-SecDF-YajC-YidC supercomplex in the E. coli inner membrane.
Protein translocase subunit SecD	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	secD	1 copy in the E. coli K-12 Complex Portal CPX-1095 entry	UNKNOWN	SecDF-YajC module constituent that links proton-motive-force assisted Sec protein transport to the SecYEG channel. `ComplexPortal:CPX-1095` Complex Portal CPX-1095 curates UniProtKB:P0AG90/secD as a one-copy participant in the E. coli K-12 SecYEG-SecDF-YajC-YidC holo-translocon. `PMID:27435098` Komar et al. 2016 describe the bacterial holo-translocon as a SecYEG-SecDF-YajC-YidC supercomplex in the E. coli inner membrane.
Protein translocase subunit SecF	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	secF	1 copy in the E. coli K-12 Complex Portal CPX-1095 entry	UNKNOWN	SecDF-YajC module constituent in the proton-motive-force assisted branch of the Sec holo-translocon. `ComplexPortal:CPX-1095` Complex Portal CPX-1095 curates UniProtKB:P0AG93/secF as a one-copy participant in the E. coli K-12 SecYEG-SecDF-YajC-YidC holo-translocon. `PMID:27435098` Komar et al. 2016 describe the bacterial holo-translocon as a SecYEG-SecDF-YajC-YidC supercomplex in the E. coli inner membrane.
Sec translocon accessory complex subunit YajC	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	yajC	1 copy in the E. coli K-12 Complex Portal CPX-1095 entry	UNKNOWN	Accessory membrane constituent present with SecD and SecF in the seven-participant E. coli holo-translocon source complex. `ComplexPortal:CPX-1095` Complex Portal CPX-1095 curates UniProtKB:P0ADZ7/yajC as a one-copy participant in the E. coli K-12 SecYEG-SecDF-YajC-YidC holo-translocon. `PMID:27435098` Komar et al. 2016 describe the bacterial holo-translocon as a SecYEG-SecDF-YajC-YidC supercomplex in the E. coli inner membrane.
Membrane protein insertase YidC	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	yidC	1 copy in the E. coli K-12 Complex Portal CPX-1095 entry	UNKNOWN	Membrane insertase constituent that cooperates with the SecY lateral gate during insertion and folding of inner-membrane proteins. `ComplexPortal:CPX-1095` Complex Portal CPX-1095 curates UniProtKB:P25714/yidC as a one-copy participant in the E. coli K-12 SecYEG-SecDF-YajC-YidC holo-translocon. `PMID:27435098` Komar et al. 2016 describe the bacterial holo-translocon as a SecYEG-SecDF-YajC-YidC supercomplex in the E. coli inner membrane.

Source composition assertions

Holo-translocon SecYEG-SecDF-YajC-YidC complex (ComplexPortal:CPX-1095)

Escherichia coli (strain K12) (NCBITaxon:83333) · Heteroheptamer · ECO:0000353 · retrieved 2026-10-02

Participant	Source type	Source name	Stoichiometry
`UniProtKB:P0ADZ7` — Sec translocon accessory complex subunit YajC	protein	yajC	1
`UniProtKB:P0AG93` — Protein translocase subunit SecF	protein	secF	1
`UniProtKB:P0AG90` — Protein translocase subunit SecD	protein	secD	1
`UniProtKB:P25714` — Membrane protein insertase YidC	protein	yidC	1
`UniProtKB:P0AG99` — Protein-export membrane protein SecG	protein	secG	1
`UniProtKB:P0AG96` — Protein translocase subunit SecE	protein	secE	1
`UniProtKB:P0AGA2` — Protein translocase subunit SecY	protein	secY	1

Curator-scoped import: E. coli K-12 SecYEG-SecDF-YajC-YidC holo-translocon source composition for this record. Source evidence: physical interaction evidence. The accession was resolved through the Complex Portal accession endpoint; no equivalence xref was inferred.

Canonical examples

NCBITaxon:83333 Escherichia coli K-12 — Source strain for the Complex Portal CPX-1095 SecYEG-SecDF-YajC-YidC holo-translocon entry. [ComplexPortal:CPX-1095]

Functions

protein transport by the Sec complex GO:0043952 — The SecYEG-SecDF-YajC-YidC holo-translocon carries out Sec-pathway protein transport across the bacterial plasma membrane.
- GO:0043952 GO:0043952 defines protein transport across the bacterial cytoplasmic membrane by the Sec complex.
- ComplexPortal:CPX-1095 Complex Portal cross-references protein transport by the Sec complex on the E. coli K-12 holo-translocon.
membrane insertase activity GO:0032977 — Through its YidC-containing holo-translocon assembly, the complex supports insertion of membrane proteins from the SecY lateral gate into the inner-membrane lipid bilayer.
- GO:0032977 GO:0032977 is the molecular-function term for membrane insertase activity.
- ComplexPortal:CPX-1095 Complex Portal describes YidC as facilitating passage from the SecY lateral gate and folding or assembly of inner-membrane proteins and complexes.

Physical properties

SUBUNIT_COUNT: 7 (E. coli K-12 heteroheptameric Complex Portal CPX-1095 entry) [ComplexPortal:CPX-1095]

Mechanism graphs

Sec holo-translocon couples transport and insertion (FUNCTION)

SecYEG, SecDF-YajC, and YidC assemble as the bacterial holo-translocon, where the SecYEG core supplies the pore and lateral gate, SecDF supports proton-motive-force assisted translocation, and YidC cooperates with the lateral gate for membrane-protein insertion.

Subject	Predicate	Object	Evidence
SecYEG translocon complex	forms pore and lateral gate of	Holo-translocon SecYEG-SecDF-YajC-YidC complex	`ComplexPortal:CPX-1095` Complex Portal describes SecYEG as the central pore and lateral gate of CPX-1095.
SecDF-YajC module	assembles with	SecYEG translocon complex	`ComplexPortal:CPX-1095` CPX-1095 curates SecD, SecF, YajC, SecY, SecE, and SecG as participants in one source complex. `PMID:27435098` Komar et al. 2016 identify the bacterial holo-translocon as a SecYEG-SecDF-YajC-YidC supercomplex.
Membrane protein insertase YidC	assembles with	Holo-translocon SecYEG-SecDF-YajC-YidC complex	`ComplexPortal:CPX-1095` CPX-1095 curates P25714/YidC as a one-copy participant in the E. coli K-12 complex.
proton-motive force	assists	SecDF-YajC module	`ComplexPortal:CPX-1095` Complex Portal describes SecDF as stimulating protein translocation through SecYEG with proton-motive-force assistance.
Membrane protein insertase YidC	facilitates insertion into	inner-membrane lipid bilayer	`ComplexPortal:CPX-1095` CPX-1095 describes YidC facilitating passage from the SecY lateral gate into the bilayer and then folding or assembly of inner-membrane proteins. `PMID:27924919` Botte et al. 2016 resolved a central cavity in the SecYEG-SecDF-YidC holo-translocon model that informs membrane-protein insertion.
Holo-translocon SecYEG-SecDF-YajC-YidC complex	enables	protein transport by the Sec complex	`ComplexPortal:CPX-1095` Complex Portal cross-references GO:0043952 on the E. coli K-12 holo-translocon.
Holo-translocon SecYEG-SecDF-YajC-YidC complex	enables	membrane insertase activity	`ComplexPortal:CPX-1095` Complex Portal cross-references GO:0032977 on the E. coli K-12 holo-translocon.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral protein-family groundings for SecY, SecE, SecG, SecD, SecF, YajC, and YidC before replacing their reviewed-label-only rows. CPX-1095 exactly identifies each E. coli K-12 participant, but accession-specific UniProtKB identifiers belong in complex_compositions and none of the seven constituents has a verified exact source-neutral protein-family CURIE in this record.
INTERPRETATION (RESOLVED): Should SecDF-YajC and YidC be folded into the SecYEG translocon record or modeled as constituents of a larger SecYEG-SecDF-YajC-YidC holo-translocon? The existing SecYEG translocon record captures the heterotrimeric protein-conducting channel core, while CPX-1095 scopes the E. coli holo-translocon as SecYEG assembled with SecDF-YajC and YidC. The larger holo-translocon is therefore a distinct supercomplex that has the SecYEG core as a named part.
INTERPRETATION (RESOLVED): Should SecA be modeled as a constituent of the SecYEG-SecDF-YajC-YidC holo-translocon? SecA drives post-translational substrates through Sec-family channels, but CPX-1095 scopes the holo-translocon itself to SecYEG, SecDF-YajC, and YidC.

Evidence

ComplexPortal:CPX-1095 Complex Portal entry for the E. coli K-12 Holo-translocon SecYEG-SecDF-YajC-YidC complex.
GO:0031522 — cell envelope Sec protein transport complex Gene Ontology cellular-component parent term for the cell envelope Sec protein transport complex.
GO:0043952 Gene Ontology biological-process term for protein transport by the Sec complex.
GO:0032977 Gene Ontology molecular-function term for membrane insertase activity.
PDB:5MG3 RCSB Protein Data Bank entry for an EM-fitted bacterial holo-translocon model that includes SecYEG, SecDF, and YidC.
PMID:27435098 PubMed identifier for Komar et al. 2016, Membrane protein insertion and assembly by the bacterial holo-translocon SecYEG-SecDF-YajC-YidC.
DOI:10.1042/BCJ20160545 DOI for Komar et al. 2016, Membrane protein insertion and assembly by the bacterial holo-translocon SecYEG-SecDF-YajC-YidC.
PMID:27924919 PubMed identifier for Botte et al. 2016, A central cavity within the holo-translocon suggests a mechanism for membrane protein insertion.
DOI:10.1038/srep38399 DOI for Botte et al. 2016, A central cavity within the holo-translocon suggests a mechanism for membrane protein insertion.

Curation history

2026-10-02T13:34:20Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-02T13:38:48Z codex · EXPANDED_RECORD — Added CPX-1095 synonymy, GO Sec-complex parentage, a SecYEG core has-part link, seven one-copy CPX participant component rows, E. coli K-12 canonical context, GO-grounded Sec transport and membrane insertase functions, subunit-count evidence, a compact holo-translocon function graph, and boundary discussions for component family grounding plus SecA exclusion.
2026-10-02T13:39:33Z complex_portal · ADD_EVIDENCE — Added taxon-specific composition ComplexPortal:CPX-1095 (7 participants); exact accession and taxon verified at import.
2026-10-02T13:45:07Z codex · REVIEW_FIX — Removed the broad GO:0005886 grounding from the inner-membrane lipid bilayer causal-graph node because the term label is plasma membrane, not a source-exact bacterial inner-membrane lipid bilayer.
2026-10-02T13:59:33Z codex · REVIEW_FIX — Resolved issue #1916 by documenting why SecDF-YajC and YidC are modeled as holo-translocon constituents around a SecYEG core rather than folded into the SecYEG translocon complex record.

Source: data/structures/secretion_system/holo_translocon_secyeg_secdf_yajc_yidc_complex.yaml