Serum amyloid P component

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Amyloid P component, serum
Cartoon model of SAP showing helices in red, sheets in yellow and coils in green.
Available structures: 1gyk, 1lgn, 1sac, 2a3w, 2a3x, 2a3y
Identifiers
Symbols APCS; MGC88159; PTX2; SAP
External IDs OMIM: 104770 MGI: 98229 HomoloGene: 1239
RNA expression pattern

More reference expression data
Orthologs
Human Mouse
Entrez 325 20219
Ensembl ENSG00000132703 ENSMUSG00000026542
Uniprot P02743 Q4JFI8
Refseq NM_001639 (mRNA)
NP_001630 (protein)		 NM_011318 (mRNA)
NP_035448 (protein)
Location Chr 1: 157.82 - 157.83 Mb Chr 1: 174.73 - 174.73 Mb
Pubmed search [1] [2]

Amyloid P component, serum (SAP) is the identical serum form of amyloid P component (AP), a 25kDa pentameric protein first identified as the pentagonal constituent of in vivo pathological deposits called "amyloid".[1]. APCS is its human gene.[2]

In amyloidosis

AP makes up 14% of the dry mass of amyloid deposits[3] and is thought to be an important contributor to the pathogenesis of a related group of diseases called the Amyloidoses.[4] These conditions are characterised by the ordered aggregation of normal globular proteins and peptides into insoluble fibres which disrupt tissue architecture and are associated with cell death. AP is thought to decorate and stabilise aggregates by preventing proteolytic cleavage and hence inhibiting fibril removal via the normal protein scavenging mechanisms.[5] This association is utilised in the routine clinical diagnostic technique of SAP scintigraphy whereby radio-labelled protein is injected into patients to locate areas of amyloid deposition.[6] The SAP-amyloid association has also been identified as a possible drug target for anti-amyloid therapy, with the recent development and first stage clinical trials of a compound called CPHPC (R-1-[6-[R-2-carboxy-pyrrolidin-1-yl]-6-oxohexanoyl] pyrrolidine-2-carboxylic acid), a small molecule able to strip AP from deposits by reducing levels of circulating SAP.[7]

Structure

SAP is a member of the pentraxins family, characterised by calcium dependent ligand binding and distinctive flattened β-jellyroll structure similar to that of the legume lectins.[8] 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 95 Å across and 35 Å deep. Human SAP has 51% sequence homology with C-reactive protein (CRP), a classical acute phase response plasma protein, and is a more distant relative to the "long" pentraxins such as PTX3 (a cytokine modulated molecule) and several neuronal pentraxins. Both SAP and CRP are evolutionary conserved in all vertebrates and also found in distant invertebrates such as the horseshoe crab (Limulus polyphemus).[9]

References

  1. ^ Cathcart ES, Shirahama T, Cohen AS (1967). "Isolation and identification of a plasma component of amyloid". Biochim. Biophy. Acta. 147: 392–393. 
  2. ^ "Entrez Gene: APCS amyloid P component, serum".
  3. ^ Skinner M, Pepys MB, Cohen AS, Heller LM, Lian JB (1980). in Freitas, Antonio Falcão de; Glenner, George G.; Costa, Pedro Pinho e. editors: Amyloid and amyloidosis: proceedings of the Third International Symposium on Amyloidosis, Póvoa de Varzim, Portugal, 23-28 September 1979. Amsterdam: Excerpta Medica, pages 384-391. ISBN 0-444-90124-8. 
  4. ^ Botto M, Hawkins PN, Bickerstaff MC, Herbert J, Bygrave AE, McBride A, Hutchinson WL, Tennent GA, Walport MJ, Pepys MB (1997). "Amyloid deposition is delayed in mice with targeted deletion of the serum amyloid P component gene". Nat. Med. 3 (8): 855–9. doi:10.1038/9544. PMID 9256275. 
  5. ^ Tennent GA, Lovat LB, Pepys MB (1995). "Serum amyloid P component prevents proteolysis of the amyloid fibrils of Alzheimer disease and systemic amyloidosis". Proc. Natl. Acad. Sci. U.S.A. 92 (10): 4299–303. doi:10.1073/pnas.92.10.4299. PMID 7753801. 
  6. ^ Hawkins PN, Pepys MB (1995). "Imaging amyloidosis with radiolabelled SAP". Eur J Nucl Med 22 (7): 595–9. PMID 7498219. 
  7. ^ Pepys MB, Herbert J, Hutchinson WL, Tennent GA, Lachmann HJ, Gallimore JR, Lovat LB, Bartfai T, Alanine A, Hertel C, Hoffmann T, Jakob-Roetne R, Norcross RD, Kemp JA, Yamamura K, Suzuki M, Taylor GW, Murray S, Thompson D, Purvis A, Kolstoe S, Wood SP, Hawkins PN (2002). "Targeted pharmacological depletion of serum amyloid P component for treatment of human amyloidosis". Nature 417 (6886): 254–9. doi:10.1038/417254a. PMID 12015594. 
  8. ^ Emsley J, White HE, O'Hara BP, Oliva G, Srinivasan N, Tickle IJ, Blundell TL, Pepys MB, Wood SP (1994). "Structure of pentameric human serum amyloid P component". Nature 367 (6461): 338–45. doi:10.1038/367338a0. PMID 8114934. 
  9. ^ Pepys MB, Booth DR, Hutchinson WL, Gallimore JR, Collins PM, Hohenester E (1997). "Amyloid P component. A critical review". Amyloid-International Journal of Experimental and Clinical Investigation 4: 274–295. 
v • d • e
Protein: glycoproteins
v • d • e
Acute phase proteins
Amyloid
SAP - SAA
Other positive
Negative
v • d • e
Metabolic disease: amyloidosis (E85, 277.3)
Forms of amyloid
Systemic amyloidosis
Organ-limited amyloidosis

Wikipedia content modification information:

  • This page was last modified on 24 September 2008, at 09:03.

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