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APCS
Available structures
PDB	Ortholog search: PDBe RCSB
List of PDB id codes
	4AYU, 1GYK, 1LGN, 1SAC, 2A3W, 2A3X, 2A3Y, 2W08, 3D5O, 3KQR, 4AVS, 4AVT, 4AVV
Identifiers
Aliases	APCS, HEL-S-92n, PTX2, SAP, amyloid P component, serum
External IDs	OMIM: 104770; MGI: 98229; HomoloGene: 123932; GeneCards: APCS; OMA:APCS - orthologs
Gene location (Human)
Chr.	Chromosome 1 (human)
End	159,588,865 bp
Gene location (Mouse)
Chr.	Chromosome 1 (mouse)
End	172,722,608 bp
RNA expression pattern
	Top expressed in
	right lobe of liver; ; gallbladder; ; islet of Langerhans; ; pancreatic ductal cell; ; body of pancreas; ; skin of thigh; ; human kidney; ; cervix; ; ectocervix; ; Descending thoracic aorta;
	Top expressed in
	left lobe of liver; ; sexually immature organism; ; right kidney; ; epithelium of small intestine; ; human fetus; ; migratory enteric neural crest cell; ; ureter; ; atrioventricular junction; ; thoracic diaphragm; ; abdominal wall;
	More reference expression data
	More reference expression data
Gene ontology
Molecular function	calcium ion binding; unfolded protein binding; metal ion binding; virion binding; complement component C1q complex binding; carbohydrate binding; identical protein binding; low-density lipoprotein particle binding;
Cellular component	blood microparticle; extracellular matrix; extracellular exosome; nucleus; extracellular space; extracellular region; collagen-containing extracellular matrix;
Biological process	negative regulation of monocyte differentiation; negative regulation of acute inflammatory response; negative regulation of viral entry into host cell; chaperone-mediated protein complex assembly; negative regulation of viral process; negative regulation of glycoprotein metabolic process; protein folding; acute-phase response; negative regulation of exo-alpha-sialidase activity; negative regulation of wound healing; innate immune response; complement activation, classical pathway;
	Sources:Amigo / QuickGO
Orthologs
	325
	20219
	ENSG00000132703
	ENSMUSG00000026542
	P02743
	P12246
	NM_001639
	NM_011318
	NP_001630
	NP_035448
	Wikidata
View/Edit Human	View/Edit Mouse

The serum amyloid P component (SAP) is the identical serum form of the amyloid P component (AP), a 25 kDa pentameric protein first identified as the pentagonal constituent of in vivo pathological deposits called "amyloid".^[5] APCS is its human gene.^[6]

In amyloidosis

SAP makes up 14% of the dry mass of amyloid deposits^[7] and is thought to be an important contributor to the pathogenesis of a related group of diseases called the Amyloidoses.^[8] 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. SAP is thought to decorate and stabilise aggregates by preventing proteolytic cleavage and hence inhibiting fibril removal via the normal protein scavenging mechanisms.^[9] 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.^[10] 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.^[11]

Structure

SAP is a member of the pentraxins family, characterised by calcium-dependent ligand binding and a distinctive flattened β-jellyroll structure similar to that of the legume lectins.^[12] The name "pentraxin" is derived from the Greek words for five (penta) and berries (ragos), relating to the radial symmetry of five monomers forming a ring approximately 95 across and 35 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 are also found in distant invertebrates such as the horseshoe crab (Limulus polyphemus).^[13]

References

^ ^a ^b ^c GRCh38: Ensembl release 89: ENSG00000132703 – Ensembl, May 2017
^ ^a ^b ^c GRCm38: Ensembl release 89: ENSMUSG00000026542 – Ensembl, May 2017
^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^ Cathcart ES; Shirahama T; Cohen AS (1967). "Isolation and identification of a plasma component of amyloid". Biochim. Biophys. Acta. 147 (2): 392–393. doi:10.1016/0005-2795(67)90420-5.
^ "Entrez Gene: APCS amyloid P component, serum".
^ Skinner M; Pepys MB; Cohen AS; Heller LM; Lian JB (1980). Freitas, Antonio Falcão de; Glenner, George G.; Costa, Pedro Pinho e. (eds.). Amyloid and amyloidosis: proceedings of the Third International Symposium on Amyloidosis, Póvoa de Varzim, Portugal, 23–28 September 1979. Amsterdam: Excerpta Medica. pp. 384–391. ISBN 0-444-90124-8.
^ Botto M, Hawkins PN, Bickerstaff MC, Herbert J, Bygrave AE, McBride A, Hutchinson WL, Tennent GA, Walport MJ, Pepys MB (August 1997). "Amyloid deposition is delayed in mice with targeted deletion of the serum amyloid P component gene". Nature Medicine. 3 (8): 855–9. doi:10.1038/9544. PMID 9256275. S2CID 19553541.
^ Tennent GA, Lovat LB, Pepys MB (May 1995). "Serum amyloid P component prevents proteolysis of the amyloid fibrils of Alzheimer disease and systemic amyloidosis" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 92 (10): 4299–303. doi:10.1073/pnas.92.10.4299. PMC 41931. PMID 7753801.
^ Hawkins PN, Pepys MB (July 1995). "Imaging amyloidosis with radiolabelled SAP". European Journal of Nuclear Medicine. 22 (7): 595–9. doi:10.1007/BF01254559. PMID 7498219. S2CID 8549928.
^ 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 (May 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. S2CID 733818.
^ 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. S2CID 4284282.
^ Pepys MB, Booth DR, Hutchinson WL, Gallimore JR, Collins PM, Hohenester E (1997). "Amyloid P component. A critical review". Amyloid. 4 (4): 274–295. doi:10.3109/13506129709003838.