C1QA
GeneName
C1QA
Summary
C1QA, also known as C1q, is a 26 kDa protein that is part of the complement system and is primarily expressed in the extracellular region. It forms a collagen trimer and is a component of the complement component C1 complex, playing a pivotal role in the classical pathway of complement activation. C1QA is involved in various biological processes, including cell-cell signaling, astrocyte and microglial cell activation, and synapse organization and pruning. Its binding to amyloid-beta suggests a role in neurodegenerative processes, particularly in the context of synaptic function and neuron remodeling.
Importance
C1QA is relevant to: - The innate immune response and its regulation of neuroinflammation, impacting conditions such as Alzheimer’s disease. - Synaptic health and plasticity through its role in complement-mediated synapse pruning, which is crucial for neural circuit refinement. - Eye development and patterning in vertebrates, highlighting its role in developmental biology. - Potential therapeutic targets in neurodegenerative diseases due to its interactions with amyloid-beta and involvement in synapse dynamics.
Top Products
For researchers investigating C1QA, we recommend two primary antibodies that have garnered attention in the field. The first is the well-cited monoclonal antibody, Anti-C1q antibody [JL-1] (ab71940), which is particularly noted for its application in ELISA and has received 46 citations, reflecting its reliability and trust within the research community. Additionally, we offer the recombinant antibody, Anti-C1q antibody [7H8] (ab11861), which has been validated for use in immunohistochemistry (IHC) and has 28 citations. This recombinant option provides the advantage of batch-to-batch consistency, making it an excellent choice for researchers seeking dependable results in their studies of C1QA. The Anti-C1q antibody [JL-1] ELISA Kit (ab71940), supported by 46 citations, is an excellent option for researchers looking to accurately measure C1QA levels in their samples.
Abcam Product Citation Summary
The data indicates that C1QA is being studied in various human contexts, particularly in relation to neurological conditions and the effects of injury. The use of antibodies in western blotting highlights the importance of C1QA in understanding its role in human health and disease.
Abcam Product Citation Table
Domain
The C1q domain is the ligand-recognition domain, which specifically recognizes and binds the Fc regions of IgG or IgM immunoglobulins.
The collagen-like domain interacts with C1R and C1S proenzymes.
Function
Core component of the complement C1 complex, a multiprotein complex that initiates the classical pathway of the complement system, a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system (PubMed:12847249, PubMed:19006321, PubMed:24626930, PubMed:29449492, PubMed:3258649, PubMed:34155115, PubMed:6249812, PubMed:6776418). The classical complement pathway is initiated by the C1Q subcomplex of the C1 complex, which specifically binds IgG or IgM immunoglobulins complexed with antigens, forming antigen-antibody complexes on the surface of pathogens: C1QA, together with C1QB and C1QC, specifically recognizes and binds the Fc regions of IgG or IgM via its C1q domain (PubMed:12847249, PubMed:19006321, PubMed:24626930, PubMed:29449492, PubMed:3258649, PubMed:6776418). Immunoglobulin-binding activates the proenzyme C1R, which cleaves C1S, initiating the proteolytic cascade of the complement system (PubMed:29449492). The C1Q subcomplex is activated by a hexamer of IgG complexed with antigens, while it is activated by a pentameric IgM (PubMed:19706439, PubMed:24626930, PubMed:29449492). The C1Q subcomplex also recognizes and binds phosphatidylserine exposed on the surface of cells undergoing programmed cell death, possibly promoting activation of the complement system (PubMed:18250442).
Involvement in disease
C1q deficiency 1
C1QD1
An autosomal recessive disorder caused by impaired activation of the complement classical pathway. It generally leads to severe immune complex disease characterized by recurrent skin lesions, chronic infections, an increased risk of systemic lupus erythematosus, and glomerulonephritis.
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
O-linked glycans are assumed to be the Glc-Gal disaccharides typically found as secondary modifications of hydroxylated lysines in collagen-like domains.
Cellular localization
- Secreted
- Cell surface
- Specifically binds IgG or IgM immunoglobulins complexed with antigens, forming antigen-antibody complexes on the surface of pathogens.
Alternative names
Complement C1q subcomponent subunit A, C1QA
Database links
swissprot:P02745 entrezGene:713 swissprot:P02746 entrezGene:714 entrezGene:712 swissprot:P02747 omim:120550 omim:120570 omim:120575