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{{protein
{{infobox protein
| Name = Human Serum amyloid A1
| Name = [[SAA1|Human Serum amyloid A1]]
| caption =  
| caption =  
| image =  
| image =  
| width =  
| width =  
| HGNCid = 10513
| HGNCid = 10513
| Symbol = SAA1
| Symbol = [[SAA1]]
| AltSymbols =  
| AltSymbols =  
| EntrezGene = 6288
| EntrezGene = 6288
| OMIM = 104750
| OMIM = 104750
| RefSeq = NM_199161
| RefSeq = NM_199161
| UniProt = P02735
| UniProt = P0DJI8
| PDB =  
| PDB =  
| ECnumber =  
| ECnumber =  
Line 18: Line 18:
| LocusSupplementaryData =  
| LocusSupplementaryData =  
}}
}}
{{protein
{{infobox protein
| Name = Human Serum amyloid A2
| Name = Human Serum amyloid A2
| caption =  
| caption =  
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| LocusSupplementaryData =  
| LocusSupplementaryData =  
}}
}}
{{protein
{{infobox protein
| Name = Human Serum amyloid A3, pseudogene
| Name = Human Serum amyloid A3, pseudogene
| caption =  
| caption =  
Line 56: Line 56:
| LocusSupplementaryData =  
| LocusSupplementaryData =  
}}
}}
{{protein
{{infobox protein
| Name = Human Serum amyloid A4
| Name = Human Serum amyloid A4
| caption =  
| caption =  
Line 75: Line 75:
| LocusSupplementaryData =  
| LocusSupplementaryData =  
}}
}}
{{SI}}


{{EH}}
'''Serum amyloid A''' (SAA) proteins are a family of [[apolipoprotein]]s associated with [[high-density lipoprotein]] (HDL) in plasma. Different isoforms of SAA are expressed constitutively (constitutive SAAs) at different levels or in response to inflammatory stimuli ([[acute-phase protein|acute phase]] SAAs). These proteins are produced predominantly by the liver.<ref>{{cite journal | vauthors = Uhlar CM, Whitehead AS | title = Serum amyloid A, the major vertebrate acute-phase reactant | journal = European Journal of Biochemistry | volume = 265 | issue = 2 | pages = 501–23 | date = October 1999 | pmid = 10504381 | doi = 10.1046/j.1432-1327.1999.00657.x | url = http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=0014-2956&date=1999&volume=265&issue=2&spage=501 }}</ref>  The conservation of these proteins throughout invertebrates and vertebrates suggests that SAAs play a highly essential role in all animals.<ref>{{cite journal | vauthors = Manley PN, Ancsin JB, Kisilevsky R | title = Rapid recycling of cholesterol: the joint biologic role of C-reactive protein and serum amyloid A | journal = Medical Hypotheses | volume = 66 | issue = 4 | pages = 784–92 | year = 2006 | pmid = 16337748 | doi = 10.1016/j.mehy.2005.10.018 }}</ref>
==Overview==
'''Serum amyloid A''' (SAA) proteins are a family of [[apolipoprotein]]s associated with [[high-density lipoprotein]] (HDL) in plasma. Different isoforms of SAA are expressed constitutively (constitutive SAAs) at different levels or in response to inflammatory stimuli ([[acute phase protein|acute phase]] SAAs). These proteins are predominantly produced by the liver.<ref>Uhlar and Whitehead. Serum amyloid A, the major vertebrate acute-phase reactant Eur. J. Biochem., 1999, volume 265, pages 501-523.</ref>  The conservation of these proteins throughout invertebrates and vertebrates suggests SAAs play a highly essential role in all animals.<ref>Manley et al. Rapid recycling of cholesterol: the joint biologic role of C-reactive protein and serum amyloid A. Med Hypotheses, 2006, Volume 66, pages 784-92.</ref>


==Acute phase serum amyloid A proteins==  
==Acute-phase serum amyloid A proteins==
Acute phase serum amyloid A proteins (A-SAAs) are secreted during the acute phase of [[inflammation]]. These proteins have several roles, including the transport of [[cholesterol]] to the [[liver]] for secretion into the [[bile]], the recruitment of immune cells to inflammatory sites and the induction of [[enzyme]]s that degrade [[extracellular matrix]]. A-SAAs are implicated in several chronic inflammatory diseases, such as [[amyloidosis]], [[atherosclerosis]], and [[rheumatoid arthritis]].<ref name=Zhang>Zhang et al. Serum Amyloid A-Luciferase Transgenic Mice: Response to Sepsis, Acute Arthritis, and Contact Hypersensitivity and the Effects of Proteasome Inhibition. Journal of Immunology, 2005, Volume 174, pages 8125-8134.</ref>  Three acute phase SAA [[isoform]]s have been reported in mice, called SAA1, SAA2 and SAA3. During [[inflammation]], SAA1 and SAA2 are principally expressed and induced in the [[liver]], while SAA3 is induced in many distinct tissues. SAA1 and SAA2 genes are regulated in liver cells by the proinflammatory [[cytokine]]s [[IL-1]], [[IL-6]], and [[TNF-α]]. Both SAA1 and SAA2 are induced up to a 1000-fold in mice under acute inflammatory conditions following exposure to bacterial [[lipopolysaccharide]] (LPS).<ref name=Zhang/>  Three A-SAA genes have also been identified in humans<ref>Betts et al., The human acute-phase serum amyloid A gene family: structure, evolution and expression in hepatoma cells, Scand J Immunol. 1991, Volume 34, pages 471-82.</ref>, although the third [[gene]], ''SAA3'', is believed to represent a [[pseudogene]] that does not generate [[messenger RNA]] or [[protein]].<ref>Kluve-Beckerman et al. Non-expression of the serum amyloid A three (SAA3) gene. DNA cell biol., 1991, Volume 10, pages 651-661.</ref>
Acute-phase serum amyloid A proteins (A-SAAs) are secreted during the acute phase of [[inflammation]]. These proteins have several roles, including the transport of [[cholesterol]] to the [[liver]] for secretion into the [[bile]], the recruitment of immune cells to inflammatory sites, and the induction of [[enzyme]]s that degrade [[extracellular matrix]]. A-SAAs are implicated in several chronic inflammatory diseases, such as [[amyloidosis]], [[atherosclerosis]], and [[rheumatoid arthritis]].<ref name=Zhang>{{cite journal | vauthors = Zhang N, Ahsan MH, Purchio AF, West DB | title = Serum amyloid A-luciferase transgenic mice: response to sepsis, acute arthritis, and contact hypersensitivity and the effects of proteasome inhibition | journal = Journal of Immunology | volume = 174 | issue = 12 | pages = 8125–34 | date = June 2005 | pmid = 15944321 | doi = 10.4049/jimmunol.174.12.8125 | url = http://www.jimmunol.org/cgi/pmidlookup?view=long&pmid=15944321 }}</ref>  Three acute-phase SAA [[isoform]]s have been reported in mice, called [[SAA1]], SAA2, and SAA3. During [[inflammation]], SAA1 and SAA2 are expressed and induced principally in the [[liver]], whereas SAA3 is induced in many distinct tissues. SAA1 and SAA2 genes are regulated in liver cells by the proinflammatory [[cytokine]]s [[Interleukin 1|IL-1]], [[Interleukin 6|IL-6]], and [[TNF-α]]. Both SAA1 and SAA2 are induced up to a 1000-fold in mice under acute inflammatory conditions following exposure to bacterial [[lipopolysaccharide]] (LPS).<ref name=Zhang/>  Three A-SAA genes have also been identified in humans,<ref>{{cite journal | vauthors = Betts JC, Edbrooke MR, Thakker RV, Woo P | title = The human acute-phase serum amyloid A gene family: structure, evolution and expression in hepatoma cells | journal = Scandinavian Journal of Immunology | volume = 34 | issue = 4 | pages = 471–82 | date = October 1991 | pmid = 1656519 | doi = 10.1111/j.1365-3083.1991.tb01570.x }}</ref> although the third [[gene]], ''SAA3'', is believed to represent a [[pseudogene]] that does not generate [[messenger RNA]] or [[protein]].<ref>{{cite journal | vauthors = Kluve-Beckerman B, Drumm ML, Benson MD | title = Nonexpression of the human serum amyloid A three (SAA3) gene | journal = DNA and Cell Biology | volume = 10 | issue = 9 | pages = 651–61 | date = November 1991 | pmid = 1755958 | doi = 10.1089/dna.1991.10.651 }}</ref>  Molecular weights of the human proteins are estimated at 11.7 kDa for SAA1<ref>https://www.uniprot.org/uniprot/P0DJI8</ref> and 12.8 kDa for SAA4.<ref>https://www.uniprot.org/blast/?about=P35542[19-130]&key=Chain&id=PRO_0000031583</ref>


==Constitutive serum amyloid A proteins==
Serum amyloid A (SAA) is also an acute phase marker that responds rapidly.  Similar to [[C-reactive protein|CRP]], levels of acute-phase SAA increase within hours after inflammatory stimulus, and the magnitude of increase may be greater than that of CRP. Relatively trivial inflammatory stimuli can lead to SAA responses. It has been suggested that SAA levels correlate better with disease activity in early inflammatory joint disease than do [[erythrocyte sedimentation rate|ESR]] and CRP. Although largely produced by hepatocytes, more recent studies show that SAA is produced by adipocytes as well, and its serum concentration is associated with [[body mass index]].<ref name="isbn1-4160-0287-1">{{cite book |author1=Pincus MR |author2=McPherson RA |author3=Henry JB | title = Henry's Clinical Diagnosis and Management by Laboratory Methods | publisher = Saunders Elsevier | location = | year = 2007 | pages = | isbn = 1-4160-0287-1 }}</ref>
A fourth SAA (SAA4) was identified in humans and is expressed constitutively in the liver thus is defined as a constitutive SAA (C-SAA).<ref>Steel et al., A Constitutively Expressed Serum Amyloid A Protein Gene (SAA4) Is Closely Linked to, and Shares Structural Similarities with, an Acute-Phase Serum Amyloid A Protein Gene (SAA2). Genomics, 1993, Volume 16, Pages 447-454.</ref>  A similar protein has since been identified in the mouse that is now also called SAA4; it had originally been designated SAA5.<ref>de Beer et al. Mouse serum amyloid A protein (SAA5) structure and expression.  J. Biol. Chem., 1994, Volume 269, pages 4661-4667.</ref><ref>de Beer et al. Structure of the mouse Saa4 gene and its linkage to the serum amyloid A gene family.  Genomics, 1996, Volume 34 pages 139-142.</ref>


==References==
==Constitutive serum amyloid A proteins==
<references/>
A fourth SAA (SAA4) was identified in humans and is expressed constitutively in the liver and, thus, is defined as a constitutive SAA (C-SAA).<ref>{{cite journal | vauthors = Steel DM, Sellar GC, Uhlar CM, Simon S, DeBeer FC, Whitehead AS | title = A constitutively expressed serum amyloid A protein gene (SAA4) is closely linked to, and shares structural similarities with, an acute-phase serum amyloid A protein gene (SAA2) | journal = Genomics | volume = 16 | issue = 2 | pages = 447–54 | date = May 1993 | pmid = 7686132 | doi = 10.1006/geno.1993.1209 }}</ref> A similar protein that is now also called SAA4 has since been identified in the mouse; it had originally been designated SAA5.<ref>{{cite journal | vauthors = de Beer MC, Kindy MS, Lane WS, de Beer FC | title = Mouse serum amyloid A protein (SAA5) structure and expression | journal = The Journal of Biological Chemistry | volume = 269 | issue = 6 | pages = 4661–7 | date = February 1994 | pmid = 8308037 | doi =  | url = http://www.jbc.org/cgi/pmidlookup?view=long&pmid=8308037 }}</ref><ref>{{cite journal | vauthors = de Beer MC, de Beer FC, Gerardot CJ, Cecil DR, Webb NR, Goodson ML, Kindy MS | title = Structure of the mouse Saa4 gene and its linkage to the serum amyloid A gene family | journal = Genomics | volume = 34 | issue = 1 | pages = 139–42 | date = May 1996 | pmid = 8661036 | doi = 10.1006/geno.1996.0253 }}</ref>
 
== References ==
{{Reflist}}


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[[category:immune system]]
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Latest revision as of 21:32, 23 March 2018

Human Serum amyloid A1
Identifiers
SymbolSAA1
Entrez6288
HUGO10513
OMIM104750
RefSeqNM_199161
UniProtP0DJI8
Other data
LocusChr. 11 p15.1
Human Serum amyloid A2
Identifiers
SymbolSAA2
Entrez6289
HUGO10514
OMIM104751
RefSeqNM_030754
UniProtP02735
Other data
LocusChr. 11 p15.1-p14
Human Serum amyloid A3, pseudogene
Identifiers
SymbolSAA3P
Alt. symbolsSAA3
Entrez6290
HUGO10515
UniProtP22614
Other data
LocusChr. 11 p15.1-p14
Human Serum amyloid A4
Identifiers
SymbolSAA4
Alt. symbolsC-SAA
Entrez6291
HUGO10516
OMIM104752
RefSeqNM_006512
UniProtP35542
Other data
LocusChr. 11 p15.1-p14

Serum amyloid A (SAA) proteins are a family of apolipoproteins associated with high-density lipoprotein (HDL) in plasma. Different isoforms of SAA are expressed constitutively (constitutive SAAs) at different levels or in response to inflammatory stimuli (acute phase SAAs). These proteins are produced predominantly by the liver.[1] The conservation of these proteins throughout invertebrates and vertebrates suggests that SAAs play a highly essential role in all animals.[2]

Acute-phase serum amyloid A proteins

Acute-phase serum amyloid A proteins (A-SAAs) are secreted during the acute phase of inflammation. These proteins have several roles, including the transport of cholesterol to the liver for secretion into the bile, the recruitment of immune cells to inflammatory sites, and the induction of enzymes that degrade extracellular matrix. A-SAAs are implicated in several chronic inflammatory diseases, such as amyloidosis, atherosclerosis, and rheumatoid arthritis.[3] Three acute-phase SAA isoforms have been reported in mice, called SAA1, SAA2, and SAA3. During inflammation, SAA1 and SAA2 are expressed and induced principally in the liver, whereas SAA3 is induced in many distinct tissues. SAA1 and SAA2 genes are regulated in liver cells by the proinflammatory cytokines IL-1, IL-6, and TNF-α. Both SAA1 and SAA2 are induced up to a 1000-fold in mice under acute inflammatory conditions following exposure to bacterial lipopolysaccharide (LPS).[3] Three A-SAA genes have also been identified in humans,[4] although the third gene, SAA3, is believed to represent a pseudogene that does not generate messenger RNA or protein.[5] Molecular weights of the human proteins are estimated at 11.7 kDa for SAA1[6] and 12.8 kDa for SAA4.[7]

Serum amyloid A (SAA) is also an acute phase marker that responds rapidly. Similar to CRP, levels of acute-phase SAA increase within hours after inflammatory stimulus, and the magnitude of increase may be greater than that of CRP. Relatively trivial inflammatory stimuli can lead to SAA responses. It has been suggested that SAA levels correlate better with disease activity in early inflammatory joint disease than do ESR and CRP. Although largely produced by hepatocytes, more recent studies show that SAA is produced by adipocytes as well, and its serum concentration is associated with body mass index.[8]

Constitutive serum amyloid A proteins

A fourth SAA (SAA4) was identified in humans and is expressed constitutively in the liver and, thus, is defined as a constitutive SAA (C-SAA).[9] A similar protein that is now also called SAA4 has since been identified in the mouse; it had originally been designated SAA5.[10][11]

References

  1. ↑ Uhlar CM, Whitehead AS (October 1999). "Serum amyloid A, the major vertebrate acute-phase reactant". European Journal of Biochemistry. 265 (2): 501–23. doi:10.1046/j.1432-1327.1999.00657.x. PMID 10504381.
  2. ↑ Manley PN, Ancsin JB, Kisilevsky R (2006). "Rapid recycling of cholesterol: the joint biologic role of C-reactive protein and serum amyloid A". Medical Hypotheses. 66 (4): 784–92. doi:10.1016/j.mehy.2005.10.018. PMID 16337748.
  3. ↑ 3.0 3.1 Zhang N, Ahsan MH, Purchio AF, West DB (June 2005). "Serum amyloid A-luciferase transgenic mice: response to sepsis, acute arthritis, and contact hypersensitivity and the effects of proteasome inhibition". Journal of Immunology. 174 (12): 8125–34. doi:10.4049/jimmunol.174.12.8125. PMID 15944321.
  4. ↑ Betts JC, Edbrooke MR, Thakker RV, Woo P (October 1991). "The human acute-phase serum amyloid A gene family: structure, evolution and expression in hepatoma cells". Scandinavian Journal of Immunology. 34 (4): 471–82. doi:10.1111/j.1365-3083.1991.tb01570.x. PMID 1656519.
  5. ↑ Kluve-Beckerman B, Drumm ML, Benson MD (November 1991). "Nonexpression of the human serum amyloid A three (SAA3) gene". DNA and Cell Biology. 10 (9): 651–61. doi:10.1089/dna.1991.10.651. PMID 1755958.
  6. ↑ https://www.uniprot.org/uniprot/P0DJI8
  7. ↑ https://www.uniprot.org/blast/?about=P35542[19-130]&key=Chain&id=PRO_0000031583
  8. ↑ Pincus MR; McPherson RA; Henry JB (2007). Henry's Clinical Diagnosis and Management by Laboratory Methods. Saunders Elsevier. ISBN 1-4160-0287-1.
  9. ↑ Steel DM, Sellar GC, Uhlar CM, Simon S, DeBeer FC, Whitehead AS (May 1993). "A constitutively expressed serum amyloid A protein gene (SAA4) is closely linked to, and shares structural similarities with, an acute-phase serum amyloid A protein gene (SAA2)". Genomics. 16 (2): 447–54. doi:10.1006/geno.1993.1209. PMID 7686132.
  10. ↑ de Beer MC, Kindy MS, Lane WS, de Beer FC (February 1994). "Mouse serum amyloid A protein (SAA5) structure and expression". The Journal of Biological Chemistry. 269 (6): 4661–7. PMID 8308037.
  11. ↑ de Beer MC, de Beer FC, Gerardot CJ, Cecil DR, Webb NR, Goodson ML, Kindy MS (May 1996). "Structure of the mouse Saa4 gene and its linkage to the serum amyloid A gene family". Genomics. 34 (1): 139–42. doi:10.1006/geno.1996.0253. PMID 8661036.

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