C9 Human
Description
Functional Role in the Complement System
C9 Human is the final component of the MAC, forming pores via three steps:
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Binding to C5b-8: C9 attaches to the C5b-8 complex, initiating polymerization .
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Conformational Change: Transition from globular to tubular structure, exposing TMH1 and TMH2 .
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Pore Assembly: Up to 18 C9 molecules form a cylindrical pore (≈10 nm diameter), causing osmotic cell lysis .
Pathways of Activation
The MAC is assembled via:
| Pathway | Trigger | Role of C9 Human |
|---|---|---|
| Classical | Antibody-antigen complexes | Terminal pore formation |
| Alternative | Spontaneous C3 activation | Amplifies pathogen lysis |
| Lectin | Pathogen-associated molecular patterns | Rapid immune response |
Immune Defense
C9 Human is essential for combating:
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Gram-negative bacteria: Neisseria meningitidis infections are linked to C9 deficiency .
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Virally infected cells: MAC-mediated lysis clears pathogens.
Disease Association
Key C9 Variants in AMD
Functional Assays:
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Hemolysis: p.P167S carriers show reduced lysis of sheep erythrocytes despite elevated C9 levels .
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Polymerization: p.P167S mutants aggregate spontaneously, bypassing zinc dependence .
Experimental Models
Table 1: C9 Human Molecular Properties
| Parameter | Value/Description |
|---|---|
| Gene ID | 735 (Uniprot P02748) |
| Exons | 11 (fish models) |
| Plasma Concentration | 19.7–25.2 µg/ml (variant-dependent) |
Table 2: Genetic Variants in AMD
| Variant | Secretion Level | Polymerization Efficiency | Plasma C9 (µg/ml) |
|---|---|---|---|
| p.P167S | Normal | Spontaneous (zinc-independent) | 19.7 |
| p.F62S | Elevated | Zinc-dependent (impaired) | 24.9 |
| p.A529T | Elevated | Normal | 24.9 |
Product Specs
Complement component C9 is a crucial part of the membrane attack complex (MAC), a structure formed on cell membranes during the terminal pathway of the complement system. This pathway, activated by both the classical and alternative pathways, generates enzyme complexes that bind to target surfaces. These enzymes cleave C5, releasing the anaphylatoxin C5a and activating C5b. C5b initiates the assembly of the MAC by binding C6, forming a stable complex. This complex can then bind to the target cell membrane with the help of C7. The subsequent binding of C8 allows for the insertion of multiple C9 molecules, leading to the formation of a pore-like structure in the membrane. This pore disrupts the cell's osmotic balance, ultimately leading to cell lysis and death. C9, therefore, plays a vital role in the MAC's ability to eliminate pathogens and damaged cells.
Human Complement C9, derived from human plasma, is a glycosylated polypeptide with a molecular weight of 71 kDa.
Sterile, filtered solution.
This solution contains 1 mg/ml of C9 protein in a phosphate-buffered saline (PBS) solution with a pH of 7.2.
Human C9 remains stable at 4°C for 2-4 weeks, provided the entire vial is used within that period. For extended storage, freezing at -20°C is recommended. The addition of a carrier protein (0.1% HSA or BSA) is advisable for long-term storage. To maintain protein integrity, avoid repeated freeze-thaw cycles.
The purity of this product is greater than 95%, as determined by SDS-PAGE analysis.
Each plasma donation used in the production of this product has undergone rigorous testing and is confirmed negative for antibodies against HIV-1, HIV-2, HCV, and HBsAg, ensuring its safety for use.
Human Plasma.
Product Science Overview
C9 is a single-chain glycoprotein with a molecular weight of approximately 71,000 Da . It is naturally glycosylated (7.8%) and composed of a single polypeptide chain . The gene encoding C9 is located on chromosome 5p in humans . The protein is part of the membrane attack complex (MAC), which also includes complement components C5b, C6, C7, and C8 .
Once activated, about 12-18 molecules of C9 polymerize to form pores in the target cell membranes, causing lysis and cell death . This pore formation is a critical mechanism by which bacterial cells are killed during an infection . The MAC assembles on bacterial membranes to form a pore, permitting disruption of bacterial membrane organization .
Research on C9 and the complement system has significant implications for understanding immune responses and developing therapeutic interventions for immune-related diseases. The study of C9 also contributes to the broader understanding of the complement system’s role in various pathological conditions, including autoimmune diseases and inflammatory disorders.
