Complement C1Q Subunit A Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
C1q is the initiating molecule of the classical complement pathway and plays a critical role in synaptic pruning, neuroinflammation, and neurodegeneration. The C1q complex consists of six copies each of three subunits (A, B, and C), and C1q subunit A is essential for its function. [1]
C1q subunit A is a component of the C1 complex that initiates the classical complement cascade. C1q is expressed in the brain by microglia and neurons and plays important roles in synaptic pruning, phagocytosis, and neuroinflammation. It is emerging as a therapeutic target for neurodegenerative diseases. [2]
This protein is involved in: [3]
| Attribute | Value | [4]
|-----------|-------| [5]
| Protein Name | Complement C1q Subunit A |
| Gene | C1QA |
| UniProt ID | P02787 |
| Molecular Weight | 26 kDa (subunit), 460 kDa (complex) |
| Subcellular Localization | Secreted, plasma membrane |
| Protein Family | C1q family |
The C1q molecule has a unique structural organization:
Each globular head can bind independently to different targets, enabling C1q to recognize diverse molecular patterns.
C1q mediates complement activation and immune surveillance:
In the brain, C1q is produced by microglia and astrocytes and plays important roles in development and homeostasis.
C1q contributes to AD through multiple mechanisms:
In PD, C1q:
C1q in ALS:
C1q signaling:
C1q initiates the classical pathway:
Developmental and disease-associated pruning:
| Drug/Approach | Target | Status | Description |
|---|---|---|---|
| Anti-C1q antibodies | C1q | Phase 1/2 | For MS, lupus (ANX005) |
| C1s inhibitors | C1s | Clinical | Reduce complement activation |
| CR3 antagonists | CD11b/CD18 | Preclinical | Block microglial phagocytosis |
| C3 inhibitors | C3 | Approved | Eculizumab (not CNS) |
Current investigation areas:
The study of Complement C1Q Subunit A Protein 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.
Hong S, et al. Complement and microglia mediate early synapse loss in Alzheimer mouse models. 2016. ↩︎
Thielens NM, et al. Structure and functions of C1q. 2019. ↩︎
Bialas AR, et al. Microglia-dependent synapse loss in type I interferon-mediated disease. 2020. ↩︎
Dejanovic B, et al. Complement C1q and C3 regulate synaptic plasticity in the adult brain. 2018. ↩︎
Shi Q, et al. Complement C1q is elevated in Alzheimer's disease and accelerates amyloid pathology. 2017. ↩︎