| 词条 | Anaphylatoxin |
| 释义 |
| Symbol = ANATO | Name = Anaphylotoxin-like domain | image = PDB 1c5a EBI.jpg | width = | caption = Structure of porcine C5adesArg.[1] | Pfam= PF01821 | InterPro= IPR000020 | SMART= ANATO | Prosite = PDOC00906 | SCOP = 1c5a | TCDB = | OPM family= | OPM protein= | PDB={{PDB3|2a73}}B:693-728 {{PDB3|1c5a}} :21-55 {{PDB3|1cfa}}A:698-732{{PDB3|1kjs}} :698-732 }}Anaphylatoxins, or complement peptides, are fragments (C3a, C4a and C5a) that are produced as part of the activation of the complement system.[2] Complement components C3, C4 and C5 are large glycoproteins that have important functions in the immune response and host defense.[3] They have a wide variety of biological activities and are proteolytically activated by cleavage at a specific site, forming a- and b-fragments.[4] A-fragments form distinct structural domains of approximately 76 amino acids, coded for by a single exon within the complement protein gene. The C3a, C4a and C5a components are referred to as anaphylatoxins:[4][5] they cause smooth muscle contraction, vasodilation, histamine release from mast cells, and enhanced vascular permeability.[5] They also mediate chemotaxis, inflammation, and generation of cytotoxic oxygen radicals.[5] The proteins are highly hydrophilic, with a mainly alpha-helical structure held together by 3 disulfide bridges.[5] FunctionAnaphylatoxins are able to trigger degranulation (release of substances) of endothelial cells, mast cells or phagocytes, which produce a local inflammatory response. If the degranulation is widespread, it can cause a shock-like syndrome similar to that of an allergic reaction. Anaphylatoxins indirectly mediate:
ExamplesImportant anaphylatoxins:
TerminologyAlthough some drugs (morphine, codeine, synthetic ACTH) and some neurotransmitters (norepinephrine, substance P) are important mediators of degranulation of mast cells or basophils, they are generally not called anaphylatoxins. This term is reserved only for fragments of the complement system. Human proteins containing this domainC3, C4A, C4B, C4B-1, C5, FBLN1, FBLN2See also{{col div|colwidth=30em}}
References1. ^{{cite journal | vauthors = Williamson MP, Madison VS | title = Three-dimensional structure of porcine C5adesArg from 1H nuclear magnetic resonance data | journal = Biochemistry | volume = 29 | issue = 12 | pages = 2895–905 | date = March 1990 | pmid = 2337573 | doi = 10.1021/bi00464a002 }} 2. ^{{cite journal | vauthors = Hugli TE | title = Biochemistry and biology of anaphylatoxins | journal = Complement | volume = 3 | issue = 3 | pages = 111–27 | year = 1986 | pmid = 3542363 }} 3. ^{{cite journal | vauthors = Fritzinger DC, Petrella EC, Connelly MB, Bredehorst R, Vogel CW | title = Primary structure of cobra complement component C3 | journal = Journal of Immunology | volume = 149 | issue = 11 | pages = 3554–62 | date = December 1992 | pmid = 1431125 }} 4. ^1 {{cite journal | vauthors = Ogata RT, Rosa PA, Zepf NE | title = Sequence of the gene for murine complement component C4 | journal = The Journal of Biological Chemistry | volume = 264 | issue = 28 | pages = 16565–72 | date = October 1989 | pmid = 2777798 }} 5. ^1 2 3 {{cite journal | vauthors = Gennaro R, Simonic T, Negri A, Mottola C, Secchi C, Ronchi S, Romeo D | title = C5a fragment of bovine complement. Purification, bioassays, amino-acid sequence and other structural studies | journal = European Journal of Biochemistry | volume = 155 | issue = 1 | pages = 77–86 | date = February 1986 | pmid = 3081348 | doi = 10.1111/j.1432-1033.1986.tb09460.x }} Further reading{{refbegin}}
External links
2 : Complement system|Protein families |
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