# Complex Portal API > The Complex Portal as an API, powered by EMBL-EBI — a manually curated, encyclopaedic database of stable macromolecular complexes: assemblies of two or more proteins (and sometimes nucleic acids, ligands or small molecules) that work together as a single functional unit, such as ribosomes, proteasomes, RNA and DNA polymerases, the spliceosome, respiratory-chain complexes and thousands more across many species. Search the complexes by keyword and optionally by organism, getting each complex's Complex Portal accession (CPX-…), name, organism, description and whether it is computationally predicted; read a complex's full curated record including its recommended and systematic names, synonyms, species, biological function, the participating subunits each with its molecule identifier (for example a UniProt accession) and stoichiometry, any associated ligands and diseases, the evidence type and cross-references to UniProt, Gene Ontology, Reactome, Wikidata and more; and pull just the subunit composition of a complex. Ideal for structural and systems biology, pathway and network analysis, protein-function research and bioinformatics pipelines. Complex accessions look like CPX-6036. Data from EMBL-EBI Complex Portal (IMEx consortium, CC-BY). For protein–protein interaction networks see the STRING API, for protein sequences UniProt, for biological pathways Reactome and for families & domains InterPro. ## Authentication All requests require your oanor API key in the `x-oanor-key` header. Get one at https://www.oanor.com/developer/keys. ```bash curl -H "x-oanor-key: oanor_live_…" "https://api.oanor.com/complexes-api/..." ``` ## Pricing - **Free** (Free) — 565 calls/Mo, 2 req/s - **Starter** ($7/Mo) — 21,200 calls/Mo, 6 req/s - **Pro** ($21/Mo) — 91,500 calls/Mo, 15 req/s - **Mega** ($58/Mo) — 395,000 calls/Mo, 40 req/s ## Endpoints ### Complexes #### `GET /v1/complex` — A complex full record **Parameters:** - `id` (query, required, string) — Complex Portal accession, e.g. CPX-6036 Example: `CPX-6036` **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/complexes-api/v1/complex?id=CPX-6036" ``` **Response:** ```json { "data": { "complex": { "id": "CPX-6036", "url": "https://www.ebi.ac.uk/complexportal/complex/CPX-6036", "name": "Eukaryotic translation initiation factor 3 complex", "ligands": [], "species": "Homo sapiens; 9606", "diseases": [], "function": "Required for several steps in the initiation of protein synthesis. It associates with the 40S ribosome and facilitates the recruitment of eIF subunits to form the 43S pre-initiation complex (43S PIC). It is also required for disassembly and recycling of post-termination ribosomal complexes and subsequently prevents premature joining of the 40S (CPX-5223) and 60S (CPX-5183) ribosomal subunits prior to initiation.", "synonyms": [ "eIF3 complex" ], "predicted": false, "properties": "Mol. weight = approximately 800kDa ", "participants": [ { "name": "EIF3E", "type": "protein", "database": null, "identifier": "P60228", "description": "Eukaryotic translation initiation factor 3 subunit E", "stoichiometry": 1 }, { "name": "EIF3C", "type": "protein", "database": null, "identifier": "Q99613", "description": "Eukar …(truncated, see openapi.json for full schema) ``` #### `GET /v1/participants` — A complex subunit composition **Parameters:** - `id` (query, required, string) — Complex Portal accession Example: `CPX-6036` **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/complexes-api/v1/participants?id=CPX-6036" ``` **Response:** ```json { "data": { "name": "Eukaryotic translation initiation factor 3 complex", "count": 13, "complex": "CPX-6036", "species": "Homo sapiens; 9606", "participants": [ { "name": "EIF3E", "type": "protein", "database": null, "identifier": "P60228", "description": "Eukaryotic translation initiation factor 3 subunit E", "stoichiometry": 1 }, { "name": "EIF3C", "type": "protein", "database": null, "identifier": "Q99613", "description": "Eukaryotic translation initiation factor 3 subunit C", "stoichiometry": 1 }, { "name": "EIF3D", "type": "protein", "database": null, "identifier": "O15371", "description": "Eukaryotic translation initiation factor 3 subunit D", "stoichiometry": 1 }, { "name": "EIF3M", "type": "protein", "database": null, "identifier": "Q7L2H7", "description": "Eukaryotic translation initiation factor 3 subunit M", "stoichiometry": 1 }, { "name": "EIF3I", "type": "protein", "database": null, …(truncated, see openapi.json for full schema) ``` #### `GET /v1/search` — Search macromolecular complexes **Parameters:** - `q` (query, required, string) — Search text, e.g. ribosome Example: `ribosome` - `species` (query, optional, string) — Organism, e.g. human|mouse|yeast - `limit` (query, optional, string) — Max results (1-100) **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/complexes-api/v1/search?q=ribosome" ``` **Response:** ```json { "data": { "count": 20, "query": "ribosome", "total": 231, "species": null, "complexes": [ { "id": "CPX-6036", "name": "Eukaryotic translation initiation factor 3 complex", "organism": "Homo sapiens; 9606", "predicted": false, "description": "Required for several steps in the initiation of protein synthesis. It associates with the 40S ribosome and facilitates the recruitment of eIF subunits to form the 43S pre-initiation complex (43S PIC). It is also required for disassembly and recycling", "participant_count": [ { "ac": "EBI-347740", "name": "EIF3E", "xrefs": [ { "database": "panther", "qualifier": "orthology-group", "identifier": "PTHR10317", "identifierLink": null } ], "identifier": "P60228", "description": "Eukaryotic translation initiation factor 3 subunit E", "organismName": "Homo sapiens; 9606", "stochiometry": "minValue: 1, maxValue: 1", "identifierLink": "https://www.uniprot.org/uniprotkb/P60228/entry", …(truncated, see openapi.json for full schema) ``` ### Meta #### `GET /v1/meta` — Usage notes **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/complexes-api/v1/meta" ``` **Response:** ```json { "data": { "note": "The Complex Portal — a manually curated, encyclopaedic database of stable macromolecular complexes (assemblies of proteins, and sometimes nucleic acids or small molecules, that act as a unit): ribosomes, proteasomes, RNA & DNA polymerases, the spliceosome, respiratory-chain complexes and thousands more. /v1/search?q=ribosome (optional species=human|mouse|yeast|… or a scientific name) = search complexes, returning each complex's Complex Portal accession (CPX-…), name, organism, description and whether it is computationally predicted; /v1/complex?id=CPX-6036 = a complex's full record — its name and systematic name, synonyms, species, biological function, the participating subunits with their molecule identifier (e.g. UniProt accession) and stoichiometry, linked ligands and diseases, evidence type and cross-references to UniProt, GO, Reactome, Wikidata and more; /v1/participants?id=CPX-6036 = just the subunit composition (each participant's identifier, name, type and stoichiometry). Accessions look like CPX-6036. Data from EMBL-EBI Complex Portal (IMEx/CC-BY). For protein–protein interaction networks see the STRING API, for protein sequences UniProt, for pathways Reactome.", "source": "EMBL-EBI Complex Portal (ebi.ac.uk/complexportal)", "endpoints": [ "/v1/search", "/v1/complex", "/v1/participants", "/v1/meta" ] }, "meta": { "timestamp": "2026-06-01T …(truncated, see openapi.json for full schema) ``` --- Marketplace page: https://www.oanor.com/api/complexes-api OpenAPI spec: https://www.oanor.com/api/complexes-api/openapi.json