Chemicals and Drugs

Complement C1q

A subcomponent of complement C1, composed of six copies of three polypeptide chains (A, B, and C), each encoded by a separate gene (C1QA; C1QB; C1QC). This complex is arranged in nine subunits (six disulfide-linked dimers of A and B, and three disulfide-linked homodimers of C). C1q has binding sites for antibodies (the heavy chain of IMMUNOGLOBULIN G or IMMUNOGLOBULIN M). The interaction of C1q and immunoglobulin activates the two proenzymes COMPLEMENT C1R and COMPLEMENT C1S, thus initiating the cascade of COMPLEMENT ACTIVATION via the CLASSICAL COMPLEMENT PATHWAY.

National Library of MedicineMedical Subject Headings2026

Structured Summary

Abstract

A subcomponent of complement C1, composed of six copies of three polypeptide chains (A, B, and C), each encoded by a separate gene (C1QA; C1QB; C1QC). This complex is arranged in nine subunits (six disulfide-linked dimers of A and B, and three disulfide-linked homodimers of C). C1q has binding sites for antibodies (the heavy chain of IMMUNOGLOBULIN G or IMMUNOGLOBULIN M). The interaction of C1q and immunoglobulin activates the two proenzymes COMPLEMENT C1R and COMPLEMENT C1S, thus initiating the cascade of COMPLEMENT ACTIVATION via the CLASSICAL COMPLEMENT PATHWAY.

MeSH Record

Classification

Broader headings

Related Concepts

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Drug Class

Pharmacological Action

MeSH Record

Synonyms

6 entry terms
  • C1q Complement
  • Complement 1q
  • Complement Component 1q
  • C1q, Complement
  • Complement, C1q
  • Component 1q, Complement

MeSH Record

Aspects Covered

29 allowable subheadings

Indexed with the subheadings administration & dosage, adverse effects, agonists, analysis, antagonists & inhibitors, biosynthesis, cerebrospinal fluid, chemical synthesis, chemistry, classification, deficiency, drug effects, economics, genetics, history, immunology, isolation & purification, metabolism, pharmacokinetics, pharmacology, physiology, poisoning, radiation effects, standards, supply & distribution, therapeutic use, toxicity, ultrastructure, urine.

MeSH Record

History Note

2006 (1990)

MeSH Record

Previous Indexing

  • Complement 1 (1980-1989)
  • Complement Activating Enzymes (1979-1989)

MeSH Hierarchy

Tree Number

AMA Style

References

  1. National Library of Medicine. Complement C1q. Medical Subject Headings (MeSH). 2026. Unique ID D015922. http://id.nlm.nih.gov/mesh/2026/D015922
  2. Complement C1q. In: Wikipedia. https://en.wikipedia.org/wiki/Complement_component_1q
  3. Complement C1q. In: Wikidata. https://www.wikidata.org/wiki/Q21116899