| Post Translational Modifications | C3 precursor is first processed by the removal of 4 Arg residues, forming two chains, beta and alpha, linked by a disulfide bond. During activation of the complement systems, the alpha chain is cleaved into C3a and C3b by the C3 convertase: C3b stays linked to the beta chain, while C3a is released in the plasma. The alpha chain is cleaved by the serine protease complement C2b component of the C3 convertase to generate C3a and C3b following activation by the classical, lectin and GZMK complement systems. The alpha chain is cleaved by CFB component of the C3 convertase to generate C3a and C3b following activation by the alternative complement system. C3a anaphylatoxin: C3a is further processed by carboxypeptidases to release the C-terminal arginine residue generating the acylation stimulating protein (ASP). Levels of ASP are increased in adipocytes in the postprandial period and by insulin and dietary chylomicrons. Complement C3b: Complement C3b is rapidly split in two positions by factor I (CFI) and a cofactor (CFH) to form iC3b (inactivated C3b) and C3f which is released. CFI and CFH catalyze proteolytic degradation of already-deposited complement C3b. Then iC3b is slowly cleaved (possibly by CFI) to form C3c (beta chain + alpha' chain fragment 1 + alpha' chain fragment 2), C3dg and C3f. Other proteases produce other fragments such as C3d or C3g. Complement C3b: Upon activation, the internal thioester bond reacts with carbohydrate antigens on the target surface to form amide or ester bonds, leading to covalent association with the surface of pathogens. Complement C3b: Complement C3b interacts with complement C4b via a thioester linkage. Phosphorylated by FAM20C in the extracellular medium. (Microbial infection) C3 is cleaved by Staphylococcus aureus aureolysin.this cleavage renders C3a and C3b inactive. C3b is rapidly degraded by host factors CFH and CFI preventing its deposition on the bacterial surface while C3a is further inactivated by aureolysin. (Microbial infection) Complement C3 beta chain is cleaved and inactivated by S.pyogenes SpeB. (Microbial infection) Cleaved by N.meningitidis NalP between Leu-744 and Gly-745, generating a slightly shorter C3 alpha form and a slightly longer C3 beta form. The C3b-like fragment is degraded in the presence of the complement regulators CFH and CFI, preventing its deposition on the bacterial surface. |
| Function | Precursor of non-enzymatic components of the classical, alternative, lectin and GZMK complement pathways, which consist in a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system. Complement C3b: Non-enzymatic component of C5 convertase. Generated following cleavage by C3 convertase, it covalently attaches to the surface of pathogens, where it acts as an opsonin that marks the surface of antigens for removal. Complement C3b binds covalently via its reactive thioester, to cell surface carbohydrates or immune aggregates. Together with complement C4b, it then recruits the serine protease complement C2b to form the C5 convertase, which cleaves and activate C5, the next component of the complement pathways. In the alternative complement pathway, recruits the serine protease CFB to form the C5 convertase that cleaves and activates C5. C3a anaphylatoxin: Mediator of local inflammatory process released following cleavage by C3 convertase. Acts by binding to its receptor, C3AR1, activating G protein-coupled receptor signaling, promoting the phosphorylation, ARRB2-mediated internalization and endocytosis of C3AR1. C3a anaphylatoxin stimulates the activation of immune cells such as mast cells and basophilic leukocytes to release inflammation agents, such as cytokines, chemokines and histamine, which promote inflammation development. Also acts as potent chemoattractant for the migration of macrophages and neutrophils to the inflamed tissues, resulting in neutralization of the inflammatory triggers by multiple ways, such as phagocytosis and generation of reactive oxidants. Acylation stimulating protein: Adipogenic hormone that stimulates triglyceride synthesis and glucose transport in adipocytes, regulating fat storage and playing a role in postprandial triglyceride clearance. Appears to stimulate triglyceride synthesis via activation of the PLC, MAPK and AKT signaling pathways. Acts by binding to its receptor, C5AR2, activating G protein-coupled receptor signaling, promoting the phosphorylation, ARRB2-mediated internalization and endocytosis of C5AR2. C3-beta-c: Acts as a chemoattractant for neutrophils in chronic inflammation. |
| Protein Name | Complement C3C3 And Pzp-Like Alpha-2-Macroglobulin Domain-Containing Protein 1 Cleaved Into - Complement C3 Beta Chain - C3-Beta-CC3bc - Complement C3 Alpha Chain - C3a Anaphylatoxin - Acylation Stimulating ProteinAspC3adesarg - Complement C3bComplement C3b-Alpha' Chain - Complement C3c Alpha' Chain Fragment 1 - Complement C3dg Fragment - Complement C3g Fragment - Complement C3d Fragment - Complement C3f Fragment - Complement C3c Alpha' Chain Fragment 2 |
| Database Links | Reactome: R-HSA-173736Reactome: R-HSA-174577Reactome: R-HSA-198933Reactome: R-HSA-375276Reactome: R-HSA-381426Reactome: R-HSA-418594Reactome: R-HSA-6798695Reactome: R-HSA-8957275Reactome: R-HSA-9660826Reactome: R-HSA-977606 |
| Cellular Localisation | SecretedComplement C3b: SecretedCell SurfaceCovalently Associated With The Surface Of Pathogens: The Internal Thioester Bond Reacts With Carbohydrate Antigens On The Target Surface To Form Amide Or Ester BondsC3a Anaphylatoxin: Secreted |
| Alternative Antibody Names | Anti-Complement C3 antibodyAnti-C3 And Pzp-Like Alpha-2-Macroglobulin Domain-Containing Protein 1 Cleaved Into - Complement C3 Beta Chain - C3-Beta-C antibodyAnti-C3bc - Complement C3 Alpha Chain - C3a Anaphylatoxin - Acylation Stimulating Protein antibodyAnti-Asp antibodyAnti-C3adesarg - Complement C3b antibodyAnti-Complement C3b-Alpha' Chain - Complement C3c Alpha' Chain Fragment 1 - Complement C3dg Fragment - Complement C3g Fragment - Complement C3d Fragment - Complement C3f Fragment - Complement C3c Alpha' Chain Fragment 2 antibodyAnti-C3 antibodyAnti-CPAMD1 antibody |
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