Pentraxins
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| CRP drawn from PDB 1B09 | |||||||||
| Identifiers | |||||||||
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| Symbol | Pentaxin | ||||||||
| Pfam | PF00354 | ||||||||
| InterPro | IPR001759 | ||||||||
| PROSITE | PDOC00261 | ||||||||
| SCOP | 1sac | ||||||||
| SUPERFAMILY | 1sac | ||||||||
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Pentraxins, also known as pentaxins, are an evolutionary conserved family of proteins characterised by containing a pentraxin protein domain. Proteins of the pentraxin family are involved in acute immunological responses.[1] They are a class of pattern recognition receptors (PRRs).
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[edit] Structure
Pentraxins are characterised by calcium dependent ligand binding and a distinctive flattened β-jellyroll structure similar to that of the legume lectins.[2] The name "pentraxin" is derived from the Greek word for five (penta) and berries (ragos) relating to the radial symmetry of five monomers forming a ring approximately 95Å across and 35Å deep observed in the first members of this family to be identified. The "short" pentraxins include Serum Amyloid P component (SAP) and C reactive protein (CRP). The "long" pentraxins include PTX3 (a cytokine modulated molecule) and several neuronal pentraxins.
[edit] Family members
Three of the principal members of the pentraxin family are serum proteins: namely, C-reactive protein (CRP),[3] serum amyloid P component protein (SAP),[4] and female protein (FP).[5] PTX3 (or TSG-14) protein is a cytokine-induced protein that is homologous to CRPs and SAPs, but its function has not yet been determined.
[edit] C-reactive protein
C-reactive protein is expressed during acute phase response to tissue injury or inflammation in mammals. The protein resembles antibody and performs several functions associated with host defence: it promotes agglutination, bacterial capsular swelling and phagocytosis, and activates the classical complement pathway through its calcium-dependent binding to phosphocholine.[3] CRPs have also been sequenced in an invertebrate, Limulus polyphemus (Atlantic horseshoe crab), where they are a normal constituent of the hemolymph.
[edit] Serum amyloid P component
Serum amyloid P component is a vertebrate protein that is identical to tissue forms of amyloid P component. It is found in all types of amyloid deposits, in glomerular basement menbrane and in elastic fibres in blood vessels. SAP binds to various lipoprotein ligands in a calcium-dependent manner, and it has been suggested that, in mammals, this may have important implications in atherosclerosis and amyloidosis.[4]
[edit] Hamster female protein
Hamster female protein is a SAP homologue found in Mesocricetus auratus (Golden hamster). The concentration of this plasma protein is altered by sex steroids and stimuli that elicit an acute phase response.[5]
[edit] Nervous system
Pentraxin proteins expressed in the nervous system are neural pentraxin I (NPTXI) and II (NPTXII).[6] NPTXI and NPTXII are homologous and can exist within one species. It is suggested that both proteins mediate the uptake of synaptic macromolecules and play a role in synaptic plasticity. Apexin, a sperm acrosomal protein, is a homologue of NPTXII found in Cavia porcellus (Guinea pig).[7]
[edit] Human
Human genes encoding proteins that contain this domain include:
[edit] References
- ^ Gewurz H, Zhang XH, Lint TF (1995). "Structure and function of the pentraxins". Curr. Opin. Immunol. 7 (1): 54–64. doi:10.1016/0952-7915(95)80029-8. PMID 7772283.
- ^ Emsley J, White HE, O'Hara BP, Oliva G, Srinivasan N, Tickle IJ, Blundell TL, Pepys MB, Wood SP (January 1994). "Structure of pentameric human serum amyloid P component". Nature 367 (6461): 338–45. doi:10.1038/367338a0. PMID 8114934.
- ^ a b Romero IR, Morris C, Rodriguez M, Mold C, Du Clos TW (1998). "Inflammatory potential of C-reactive protein complexes compared to immune complexes". Clin. Immunol. Immunopathol. 87 (2): 155–162. doi:10.1006/clin.1997.4516. PMID 9614930.
- ^ a b Yutani C, Shimokado K, Li XA (1998). "Serum amyloid P component associates with high density lipoprotein as well as very low density lipoprotein but not with low density lipoprotein". Biochem. Biophys. Res. Commun. 244 (1): 249–252. doi:10.1006/bbrc.1998.8248. PMID 9514915.
- ^ a b Coe JE, Ross MJ (1997). "Electrophoretic polymorphism of a hamster pentraxin, female protein (amyloid P component)". Scand. J. Immunol. 46 (2): 180–182. doi:10.1046/j.1365-3083.1997.d01-109.x. PMID 9583999.
- ^ Perin MS, Omeis IA, Hsu YC (1996). "Mouse and human neuronal pentraxin 1 (NPTX1): conservation, genomic structure, and chromosomal localization". Genomics 36 (3): 543–545. doi:10.1006/geno.1996.0503. PMID 8884281.
- ^ Reid MS, Blobel CP (1994). "Apexin, an acrosomal pentaxin". J. Biol. Chem. 269 (51): 32615–32620. PMID 7798266.
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This article incorporates text from the public domain Pfam and InterPro IPR001759
