MdtBC Complex

GO:1990203 · Other · Multiprotein complex · Proposed

A protein complex containing two transmembrane subunits; a MdtB dimer and one unit of MdtC. Capable of exporting substrates across the cell membrane. Involved in conferring antibiotic resistance of Gram-negative bacteria by transporting drugs across the membrane. [GO:1990203]

Synonyms: multidrug efflux pump MdtBC

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
Multidrug resistance protein MdtB	Protein	part of	`InterPro:IPR022831`	mdtB	2 copies per active E. coli MdtBC B2C heterotrimer	UNKNOWN	Inner-membrane RND transporter permease subunit that dimerizes with one MdtC subunit to form the functional MdtBC drug efflux complex. `GO:1990203` GO:1990203 defines the MdtBC complex as containing a MdtB dimer. `InterPro:IPR022831` InterPro IPR022831 is the Multidrug resistance protein MdtB family entry. `PMID:20038594` Kim et al. 2010 reported that active E. coli MdtBC contains two MdtB subunits.
Multidrug resistance protein MdtC	Protein	part of	`InterPro:IPR023931`	mdtC	1 copy per active E. coli MdtBC B2C heterotrimer	UNKNOWN	Inner-membrane RND transporter permease subunit that pairs with the MdtB dimer to complete the B2C multidrug efflux complex. `GO:1990203` GO:1990203 defines the MdtBC complex as containing one MdtC unit. `InterPro:IPR023931` InterPro IPR023931 is the Multidrug resistance protein MdtC family entry. `PMID:20038594` Kim et al. 2010 reported that active E. coli MdtBC contains one MdtC subunit.

Organism-specific protein examples

Named proteins in which each component's role was established, with the organism the evidence comes from. The component above is the taxon-agnostic family; these are the specific entries behind it.

Multidrug resistance protein MdtB

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P76398`	Multidrug resistance protein MdtB	mdtB	Escherichia coli K-12 (`NCBITaxon:83333`)	REVIEWED
Role and evidence (2 references) Reviewed E. coli K-12 MdtB accession matching the MdtB subunit of the MdtBC heterotrimer. `UniProtKB:P76398` UniProtKB P76398 is the reviewed E. coli K-12 entry for MdtB. `PMID:20038594` Kim et al. 2010 characterized E. coli MdtB as the dimeric partner in the active MdtBC heterotrimer.

Multidrug resistance protein MdtC

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P76399`	Multidrug resistance protein MdtC	mdtC	Escherichia coli K-12 (`NCBITaxon:83333`)	REVIEWED
Role and evidence (2 references) Reviewed E. coli K-12 MdtC accession matching the single MdtC subunit of the MdtBC heterotrimer. `UniProtKB:P76399` UniProtKB P76399 is the reviewed E. coli K-12 entry for MdtC. `PMID:20038594` Kim et al. 2010 characterized E. coli MdtC as the single-copy partner in the active MdtBC heterotrimer.

Taxonomic distribution

NCBITaxon:2 Bacteria — VARIABLE: GO:1990203 frames MdtBC as an antibiotic-resistance multidrug efflux complex of Gram-negative bacteria, so it is represented as variable within Bacteria rather than universal. [GO:1990203]

Canonical examples

NCBITaxon:562 Escherichia coli — E. coli source of the active MdtBC B2C heterotrimer characterized by Kim et al. 2010. [PMID:20038594]

Functions

xenobiotic transmembrane transporter activity GO:0042910 — MdtBC exports drug substrates across the E. coli cell membrane.
- GO:1990203 GO:1990203 defines MdtBC by drug export across the cell membrane.
- GO:0042910 GO:0042910 is the molecular-function term for xenobiotic transmembrane transporter activity.

Physical properties

SUBUNIT_COUNT: 3 (E. coli MdtBC B2C heterotrimer) [PMID:20038594]

Evidence

GO:1990203 Gene Ontology cellular-component term for the MdtBC complex.
GO:1902495 QuickGO reports GO:1990203 as an is-a child of GO:1902495 transmembrane transporter complex.
GO:0042910 Gene Ontology molecular-function term for xenobiotic transmembrane transporter activity.
InterPro:IPR022831 InterPro family entry for Multidrug resistance protein MdtB.
InterPro:IPR023931 InterPro family entry for Multidrug resistance protein MdtC.
UniProtKB:P76398 UniProtKB reviewed E. coli K-12 MdtB entry.
UniProtKB:P76399 UniProtKB reviewed E. coli K-12 MdtC entry.
PMID:20038594 PubMed identifier for the E. coli MdtBC B2C heterotrimer study cited by GO:1990203.
DOI:10.1128/JB.01448-09 DOI for the MdtBC B2C heterotrimer study as reported by PubMed.

Curation history

2026-10-01T20:27:24Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-01T20:28:45Z codex · EXPANDED_RECORD — Added GO synonymy and transmembrane-transporter parentage, MdtB and MdtC components with exact InterPro groundings and reviewed E. coli K-12 UniProt examples, the B2C heterotrimer subunit count, xenobiotic transport function, taxonomy, and PMID/DOI evidence.

Source: data/structures/other/mdtbc_complex.yaml