membrane attack complex
Definition
Target type: cellularcomponent
A protein complex produced by sequentially activated components of the complement cascade inserted into a target cell membrane and forming a pore leading to cell lysis via ion and water flow. [GOC:add, ISBN:0198547684, ISBN:068340007X, ISBN:0781735149]
The membrane attack complex (MAC) is a multi-protein complex that forms pores in the cell membranes of bacteria and other pathogens, leading to cell lysis. It is part of the complement system, a major component of the innate immune system. The MAC is assembled from proteins C5b, C6, C7, C8, and multiple copies of C9. Here is a detailed description of the cellular components:
- **C5b:** A protein fragment derived from C5, the initiating component of the MAC assembly. C5b binds to C6 and initiates the assembly process.
- **C6:** Binds to C5b, forming a complex that is then able to bind C7.
- **C7:** Binds to the C5b-C6 complex and inserts itself into the cell membrane. This insertion step is critical for anchoring the MAC to the target cell.
- **C8:** A complex consisting of three subunits (C8α, C8β, and C8γ). C8 binds to the C5b-C6-C7 complex and further stabilizes the membrane insertion.
- **C9:** The final component of the MAC. Multiple C9 molecules polymerize around the C5b-C6-C7-C8 complex, forming a pore in the cell membrane. This pore allows for the influx of water and ions, leading to cell lysis.
The MAC is a highly efficient and potent cytolytic mechanism, playing a crucial role in the defense against pathogens. However, uncontrolled MAC formation can also contribute to tissue damage in certain pathological conditions.'
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Proteins (2)
| Protein | Definition | Taxonomy |
|---|---|---|
| Complement component C9 | A complement component C9 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P02748] | Homo sapiens (human) |
| Complement C5 | A complement C5 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P01031] | Homo sapiens (human) |
Compounds (5)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| aurintricarboxylic acid | aurintricarboxylic acid : A member of the class of quinomethanes that is 3-methylidene-6-oxocyclohexa-1,4-diene-1-carboxylic acid in which the methylidene hydrogens are replaced by 4-carboxy-3-hydroxyphenyl groups. The trisodium salt is the biological stain 'chrome violet CG' while the triammonium salt is 'aluminon'. Aurintricarboxylic Acid: A dye which inhibits protein biosynthesis at the initial stages. The ammonium salt (aluminon) is a reagent for the colorimetric estimation of aluminum in water, foods, and tissues. | monohydroxybenzoic acid; quinomethanes; tricarboxylic acid | fluorochrome; histological dye; insulin-like growth factor receptor 1 antagonist |
| carprofen | carprofen : Propanoic acid in which one of the methylene hydrogens is substituted by a 6-chloro-9H-carbazol-2-yl group. A non-steroidal anti-inflammatory drug, it is no longer used in human medicine but is still used for treatment of arthritis in elderly dogs. carprofen: RN given refers to cpd without isomeric designation | carbazoles; organochlorine compound | EC 1.14.99.1 (prostaglandin-endoperoxide synthase) inhibitor; non-steroidal anti-inflammatory drug; photosensitizing agent |
| oxaprozin | oxaprozin : A monocarboxylic acid that is a propionic acid derivative having a 4,5-diphenyl-1,3-oxazol-2-yl substituent at position 3. It is non-steroidal anti-inflammatory drug commonly used to relieve the pain and inflammatory responses associated with osteoarthritis and rheumatoid arthritis. Oxaprozin: An oxazole-propionic acid derivative, cyclooxygenase inhibitor, and non-steroidal anti-inflammatory drug that is used in the treatment of pain and inflammation associated with of OSTEOARTHRITIS; RHEUMATOID ARTHRITIS; and ARTHRITIS, JUVENILE. | 1,3-oxazoles; monocarboxylic acid | analgesic; non-steroidal anti-inflammatory drug |
| raloxifene | raloxifene : A member of the class of 1-benzothiophenes that is 1-benzothiophene in which the hydrogens at positions 2, 3, and 6 have been replaced by p-hydroxyphenyl, p-[2-(piperidin-1-yl)ethoxy]benzoyl, and hydroxy groups, respectively. | 1-benzothiophenes; aromatic ketone; N-oxyethylpiperidine; phenols | bone density conservation agent; estrogen antagonist; estrogen receptor modulator |
| sulindac | sulindac : A monocarboxylic acid that is 1-benzylidene-1H-indene which is substituted at positions 2, 3, and 5 by methyl, carboxymethyl, and fluorine respectively, and in which the phenyl group of the benzylidene moiety is substituted at the para position by a methylsulfinyl group. It is a prodrug for the corresponding sulfide, a non-steroidal anti-inflammatory drug, used particularly in the treatment of acute and chronic inflammatory conditions. Sulindac: A sulfinylindene derivative prodrug whose sulfinyl moiety is converted in vivo to an active NSAID analgesic. Specifically, the prodrug is converted by liver enzymes to a sulfide which is excreted in the bile and then reabsorbed from the intestine. This helps to maintain constant blood levels with reduced gastrointestinal side effects. | monocarboxylic acid; organofluorine compound; sulfoxide | analgesic; antineoplastic agent; antipyretic; apoptosis inducer; EC 1.14.99.1 (prostaglandin-endoperoxide synthase) inhibitor; non-narcotic analgesic; non-steroidal anti-inflammatory drug; prodrug; tocolytic agent |