Coagulin

Coagulin
Identifiers
Symbol	Coagulin
Pfam	PF02035
InterPro	IPR000275
Available protein structures: Pfam structures PDB RCSB PDB; PDBe PDBsum structure summary

Coagulin is a gel-forming protein of hemolymph that hinders the spread of invaders by immobilising them^[1][2].

The protein contains a single 175- residue polypeptide chain; this is cleaved after Arg-18 and Arg-46 by a clotting enzyme contained in the hemocyte and activated by a bacterial endotoxin (lipopolysaccharide). Cleavage releases two chains of coagulin, A and B, linked by two disulphide bonds, together with the peptide C^[1][2]. Gel formation results from interlinking of coagulin molecules. Secondary structure prediction suggests the C peptide forms an alpha- helix, which is released during the proteolytic conversion of coagulogen to coagulin gel^[1]. The beta-sheet structure and 16 half-cystines found in the molecule appear to yield a compact protein stable to acid and heat.

Mammalian blood coagulation is based on the proteolytically induced polymerization of fibrinogens. Initially, fibrin monomers noncovalently interact with each other. The resulting homopolymers are further stabilized when the plasma transglutaminase (TGase) intermolecularly cross-links epsilon-(gamma-glutamyl)lysine bonds. In crustaceans, hemolymph coagulation depends on the TGase-mediated cross-linking of specific plasma-clotting proteins, but without the proteolytic cascade. In horseshoe crabs, the proteolytic coagulation cascade triggered by lipopolysaccharides and beta-1,3-glucans leads to the conversion of coagulogen into coagulin, resulting in noncovalent coagulin homopolymers through head-to-tail interaction. Horseshoe crab TGase, however, does not cross-link coagulins intermolecularly. Recently, we found that coagulins are cross-linked on hemocyte cell surface proteins called proxins. This indicates that a cross-linking reaction at the final stage of hemolymph coagulation is an important innate immune system of horseshoe crabs^[3].

References

1. ^ ^{a b c} Iwanaga S, Miyata T, Srimal S, Kawabata S (1985). "The complete amino acid sequence of coagulogen isolated from Southeast Asian horseshoe crab, Carcinoscorpius rotundicauda". J. Biochem. 98 (2): 305–318. PMID 3905780. 
2. ^ ^{a b} Iwanaga S, Miyata T, Usui K (1984). "The amino acid sequence of coagulogen isolated from southeast Asian horseshoe crab, Tachypleus gigas". J. Biochem. 95 (6): 1793–1801. PMID 6469947. 
3. ^ Kawabata S, Osaki T (2004). "Structure and function of coagulogen, a clottable protein in horseshoe crabs". Cell. Mol. Life Sci. 61 (11): 1257–1265. doi:10.1007/s00018-004-3396-5. PMID 15170505. 

This article includes text from the public domain Pfam and InterPro IPR000275

This protein-related article is a stub. You can help Wikipedia by expanding it.v · Categories: Protein domains Protein stubs Wikimedia Foundation. 2010. Игры ⚽ Поможем сделать НИР Hypercoagulability in pregnancy Coahoma High School Look at other dictionaries: coagulin — n. [L. coagulare, to curdle] A constituent of blood that aids in coagulation …   Dictionary of invertebrate zoology coagulin — noun Any substance having the ability to coagulate foreign proteins …   Wiktionary coagulin — co·ag·u·lin ko ag yə lən n 1) PRECIPITIN 2 a) a postulated tissue constituent able to induce conversion of fibrinogen to fibrin in the absence of prothrombin or thrombin b) THROMBOPLASTIN …   Medical dictionary coagulin — n. substance which causes blood to clot, coagulant (Chemistry) …   English contemporary dictionary coagulin — co·ag·u·lin …   English syllables coagulin — kōˈagyələ̇n noun ( s) Etymology: coagulate + in 1. : precipitin 2. a. : a hypothetical tissue constituent able to induce conversion of fibrinogen to fibrin in the absence of prothrombin or thrombin …   Useful english dictionary A/C — albumin/coagulin [ratio]; anterior chamber of eye; assist control [ventilation] …   Medical dictionary TBC — thyroxine binding coagulin; total body calcium; total body carbon; total body clearance; tuberculosis …   Medical dictionary A/C — • albumin/coagulin [ratio]; • anterior chamber of eye; • assist control [ventilation] …   Dictionary of medical acronyms & abbreviations TBC — • thyroxine binding coagulin; • total body calcium; • total body carbon; • total body clearance; • tuberculosis …   Dictionary of medical acronyms & abbreviations 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”