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.

Year introduced: 2006 (1990)

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Tree Number(s): D12.776.124.486.274.050.270

MeSH Unique ID: D015922

Registry Number: 80295-33-6

Entry Terms:

• C1q, Complement
• C1q Complement
• Complement, C1q
• Complement 1q
• Complement Component 1q
• Component 1q, Complement

Previous Indexing:

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

Pharmacologic Action:

• Immunologic Factors

All MeSH Categories
Chemicals and Drugs Category
Amino Acids, Peptides, and Proteins
Proteins
Blood Proteins
Immunoproteins
Complement System Proteins
Complement C1
Complement C1q