Chemicals and Drugs

Complement C1r

A 80-kDa subcomponent of complement C1, existing as a SERINE PROTEASE proenzyme in the intact complement C1 complex. When COMPLEMENT C1Q is bound to antibodies, the changed tertiary structure causes autolytic activation of complement C1r which is cleaved into two chains, A (heavy) and B (light, the serine protease), connected by disulfide bonds. The activated C1r serine protease, in turn, activates COMPLEMENT C1S proenzyme by cleaving the Arg426-Ile427 bond. No fragment is released when either C1r or C1s is cleaved.

National Library of MedicineMedical Subject Headings2026

Structured Summary

Abstract

A 80-kDa subcomponent of complement C1, existing as a SERINE PROTEASE proenzyme in the intact complement C1 complex. When COMPLEMENT C1Q is bound to antibodies, the changed tertiary structure causes autolytic activation of complement C1r which is cleaved into two chains, A (heavy) and B (light, the serine protease), connected by disulfide bonds. The activated C1r serine protease, in turn, activates COMPLEMENT C1S proenzyme by cleaving the Arg426-Ile427 bond. No fragment is released when either C1r or C1s is cleaved.

MeSH Record

Classification

Related Concepts

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Drug Class

Pharmacological Action

MeSH Record

Synonyms

6 entry terms
  • C1r Complement
  • Complement 1r
  • Complement Component 1r
  • C1r, Complement
  • Complement, C1r
  • Component 1r, 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 (1979-1989)
  • Complement Activating Enzymes (1979-1989)
  • Enzyme Precursors (1979-1982)

MeSH Hierarchy

Tree Numbers

AMA Style

References

  1. National Library of Medicine. Complement C1r. Medical Subject Headings (MeSH). 2026. Unique ID D015923. http://id.nlm.nih.gov/mesh/2026/D015923
  2. Complement C1r. In: Wikidata. https://www.wikidata.org/wiki/Q21111742