Complement C3 Immunizing Blocking Peptide

Complement component C3 plays a central role in the activation of complement system. Its activation is required for both classical and alternative complement activation pathways. The encoded preproprotein is proteolytically processed to generate alpha and beta subunits that form the mature protein, which is then further processed to generate numerous peptide products. The C3a peptide, also known as the C3a anaphylatoxin, modulates inflammation and possesses antimicrobial activity. Mutations in this gene are associated with atypical hemolytic uremic syndrome and age-related macular degeneration in human patients. [provided by RefSeq, Nov 2015]

C3: C3 plays a central role in the activation of the complement system. Its processing by C3 convertase is the central reaction in both classical and alternative complement pathways. After activation C3b can bind covalently, via its reactive thioester, to cell surface carbohydrates or immune aggregates. Defects in C3 are the cause of complement component 3 deficiency (C3D). A rare defect of the complement classical pathway. Patients develop recurrent, severe, pyogenic infections because of ineffective opsonization of pathogens. Some patients may also develop autoimmune disorders, such as arthralgia and vasculitic rashes, lupus-like syndrome and membranoproliferative glomerulonephritis. Genetic variation in C3 is associated with susceptibility to age-related macular degeneration type 9 (ARMD9). ARMD is a multifactorial eye disease and the most common cause of irreversible vision loss in the developed world. In most patients, the disease is manifest as ophthalmoscopically visible yellowish accumulations of protein and lipid that lie beneath the retinal pigment epithelium and within an elastin- containing structure known as Bruch membrane. Defects in C3 are a cause of susceptibility to hemolytic uremic syndrome atypical type 5 (AHUS5). An atypical form of hemolytic uremic syndrome. It is a complex genetic disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, renal failure and absence of episodes of enterocolitis and diarrhea. In contrast to typical hemolytic uremic syndrome, atypical forms have a poorer prognosis, with higher death rates and frequent progression to end-stage renal disease. Susceptibility to the development of atypical hemolytic uremic syndrome can be conferred by mutations in various components of or regulatory factors in the complement cascade system. Other genes may play a role in modifying the phenotype. Increased levels of C3 and its cleavage product ASP, are associated with obesity, diabetes and coronary heart disease. Short-term endurance training reduces baseline ASP levels and subsequently fat storage.

Protein type: Secreted; Secreted, signal peptide; Inhibitor

Chromosomal Location of Human Ortholog: 19p13.3-p13.2

Cellular Component: extracellular region; extracellular space; plasma membrane

Molecular Function: C5L2 anaphylatoxin chemotactic receptor binding; cofactor binding; endopeptidase inhibitor activity; lipid binding; protein binding; receptor binding; serine-type endopeptidase activity

Biological Process: blood coagulation; complement activation; complement activation, alternative pathway; complement activation, classical pathway; fatty acid metabolic process; G-protein coupled receptor protein signaling pathway; immune response; inflammatory response; positive regulation of activation of membrane attack complex; positive regulation of angiogenesis; positive regulation of developmental growth; positive regulation of G-protein coupled receptor protein signaling pathway; positive regulation of protein amino acid phosphorylation; positive regulation of type IIa hypersensitivity; proteolysis; regulation of complement activation; regulation of immune response; response to estradiol stimulus; response to glucocorticoid stimulus; response to magnesium ion; response to progesterone stimulus; signal transduction; tolerance induction

Disease: Complement Component 3 Deficiency, Autosomal Recessive; Hemolytic Uremic Syndrome, Atypical, Susceptibility To, 5; Macular Degeneration, Age-related, 9