C3 — Complement Component 3 is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Official Symbol: C3 [1]
Official Full Name: Complement Component 3 [2]
Gene ID: 735 [3]
Chromosomal Location: 19p13.3 [4]
Protein: Complement C3
The C3 gene encodes complement component 3 (C3), the central protein of the complement system. C3 is the most abundant complement protein in serum and plays a pivotal role in all three complement activation pathways (classical, lectin, and alternative). Upon activation, C3 is cleaved into C3a (anaphylatoxin) and C3b (opsonin), which mediate downstream immune responses.
The C3 gene spans approximately 42 kb on chromosome 19p13.3 and consists of 41 exons. The coding sequence is distributed across multiple exons, with alternative splicing producing multiple isoforms. The gene encodes a 1,663 amino acid preproprotein that undergoes significant post-translational modification.
C3 is synthesized as a preproprotein consisting of:
Following secretion, C3 can be cleaved by C3 convertases (C4b2a in classical/lectin pathway, C3bBb in alternative pathway) to generate:
Further cleavage produces C3c, C3d, and C3g fragments with distinct functions.
C3 and its fragments mediate multiple immune functions:
C3 is primarily synthesized in the liver (hepatocytes) but also produced locally by:
In the CNS, microglial production of C3 increases dramatically in response to injury or disease.
C3 is a promising therapeutic target:
The study of C3 — Complement Component 3 has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
C3 in ALS pathogenesis. 2021. ↩︎
C3 as therapeutic target. 2021. ↩︎