C5 Human
Description
Overview of Complement Component 5 (C5)
Complement Component 5 (C5) is a glycoprotein critical to the innate immune system, playing a pivotal role in both inflammatory responses and pathogen elimination. In humans, C5 is encoded by the C5 gene on chromosome 9 and exists as a disulfide-linked dimer of α- and β-chains (190 kDa total) . Its activation triggers downstream complement cascades, culminating in the formation of the Membrane Attack Complex (MAC) .
Key Properties of C5
Molecular Structure and Function
C5 is synthesized as a single polypeptide precursor that undergoes proteolytic processing into its α- and β-chains. These chains remain covalently linked via disulfide bonds . Upon activation by C5 convertases (generated via classical, lectin, or alternative pathways), C5 is cleaved into two fragments:
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C5a (74 amino acids): A potent anaphylatoxin with chemotactic and pro-inflammatory properties. It binds G-protein-coupled receptors (e.g., C5aR/CD88) to recruit neutrophils and induce histamine release .
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C5b: Initiates MAC assembly by binding C6, forming the C5b-6 complex. This complex sequentially recruits C7, C8, and multiple C9 molecules to create pore-forming structures in microbial membranes .
Critical Role in Pathogen Defense
C5 bridges innate and adaptive immunity:
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MAC Formation: Lytic pores disrupt microbial membranes, leading to osmotic lysis .
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Inflammatory Amplification: C5a enhances leukocyte adhesion, oxidative burst, and cytokine release .
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Immune Regulation: C5a modulates immune cell differentiation and adaptive responses .
Hereditary C5 Deficiency
Hereditary C5 deficiency results from mutations in the C5 gene (e.g., nonsense mutations in exons 1 or 36), leading to impaired MAC formation and recurrent infections . Key features include:
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Susceptibility to Neisseria spp.: Meningococcal sepsis and gonococcal arthritis .
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Immune Dysregulation: Reduced chemotaxis and impaired opsonization .
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Prevalence: Rare (~1 in 100,000), with higher frequency in specific populations (e.g., African Americans) .
Acquired Deficiency and Pathologies
C5 dysfunction is implicated in:
Targeted Therapies
Diagnostic and Research Tools
Pathogenic Mechanisms
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Bystander Lysis: C5b-7 complexes may insert into host cells, causing tissue damage .
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Genetic Variants: Mutations in C5 exon 36 (e.g., Arg1458→Stop) disrupt C5b formation .
Therapeutic Challenges
Product Specs
This section provides a concise explanation of Complement C5, its cleavage into C5a and C5b, its activation pathways, and its roles in the complement system, including its involvement in chemotaxis and the formation of the membrane attack complex.
This part specifies that the origin of the Human Complement C5 is human plasma and states its molecular weight, which is 190 kDa.
This describes the product's physical state as a solution that has been sterilized through filtration.
This section details the solution's composition in which the C5 protein is prepared, indicating it contains phosphate-buffered saline (PBS) with a pH of 7.2.
This part provides instructions for storing the Human C5 protein, advising refrigeration at 4°C for shorter-term use (2-4 weeks), freezing below -20°C for longer storage, recommending the addition of a carrier protein (HSA or BSA) for extended storage, and cautioning against repeated freeze-thaw cycles.
This indicates the purity level of the Human Complement C5 protein, stating it is greater than 95.0% as determined by SDS-PAGE analysis.
This part asserts that the plasma used to produce this protein has undergone testing for various viral infections including HIV-1, HIV-2, HCV, HTLV-I & II, Syphilis, and HBSAG and has been found negative for these viruses.
Complement Component 5, C3 and PZP-Like Alpha-2-Macroglobulin Domain-Containing Protein 4, C5a Anaphylatoxin, Prepro-C5, CPAMD4, Anaphylatoxin C5a Analog, ECLZB, C5A, C5D, C5b, C5.
Human Plasma.
Product Science Overview
Complement C5 is a glycoprotein composed of two disulfide-linked chains, the alpha (α) and beta (β) chains . The protein is naturally glycosylated and has a molecular weight of approximately 190 kDa . The α-chain contains the site for cleavage by C5 convertase, which generates the active fragments C5a and C5b .
- C5a: This is a potent anaphylatoxin involved in inflammatory responses. It recruits immune cells to the site of infection and promotes the release of pro-inflammatory cytokines .
- C5b: This fragment initiates the assembly of the MAC by binding to C6, C7, C8, and multiple C9 molecules, leading to the formation of a pore in the pathogen’s membrane, causing cell lysis .
Deficiencies or dysregulation in C5 can lead to various clinical conditions:
- C5 Deficiency: Individuals with C5 deficiency are more susceptible to recurrent bacterial infections, particularly Neisseria species .
- C5 Inhibitors: Therapeutic inhibition of C5 (e.g., with eculizumab) is used in the treatment of conditions like paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS) .
