Serum amyloid A

Serum amyloid A

protein
Name = Human Serum amyloid A1
caption =


width =
HGNCid = 10513
Symbol = SAA1
AltSymbols =
EntrezGene = 6288
OMIM = 104750
RefSeq = NM_199161
UniProt = P02735
PDB =
ECnumber =
Chromosome = 11
Arm = p
Band = 15.1
LocusSupplementaryData =
protein
Name = Human Serum amyloid A2
caption =


width =
HGNCid = 10514
Symbol = SAA2
AltSymbols =
EntrezGene = 6289
OMIM = 104751
RefSeq = NM_030754
UniProt = P02735
PDB =
ECnumber =
Chromosome = 11
Arm = p
Band = 15.1-p14
LocusSupplementaryData =
protein
Name = Human Serum amyloid A3, pseudogene
caption =


width =
HGNCid = 10515
Symbol = SAA3P
AltSymbols = SAA3
EntrezGene = 6290
OMIM =
RefSeq =
UniProt = P22614
PDB =
ECnumber =
Chromosome = 11
Arm = p
Band = 15.1-p14
LocusSupplementaryData =
protein
Name = Human Serum amyloid A4
caption =


width =
HGNCid = 10516
Symbol = SAA4
AltSymbols = C-SAA
EntrezGene = 6291
OMIM = 104752
RefSeq = NM_006512
UniProt = P35542
PDB =
ECnumber =
Chromosome = 11
Arm = p
Band = 15.1-p14
LocusSupplementaryData =

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 predominantly produced by the liver. [cite journal |author=Uhlar CM, Whitehead AS |title=Serum amyloid A, the major vertebrate acute-phase reactant |journal=Eur. J. Biochem. |volume=265 |issue=2 |pages=501–23 |year=1999 |pmid=10504381 |doi= |url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=0014-2956&date=1999&volume=265&issue=2&spage=501] The conservation of these proteins throughout invertebrates and vertebrates suggests SAAs play a highly essential role in all animals. [cite journal |author=Manley PN, Ancsin JB, Kisilevsky R |title=Rapid recycling of cholesterol: the joint biologic role of C-reactive protein and serum amyloid A |journal=Med. Hypotheses |volume=66 |issue=4 |pages=784–92 |year=2006 |pmid=16337748 |doi=10.1016/j.mehy.2005.10.018 |url=]

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.cite journal |author=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=J. Immunol. |volume=174 |issue=12 |pages=8125–34 |year=2005 |pmid=15944321 |doi= |url=http://www.jimmunol.org/cgi/pmidlookup?view=long&pmid=15944321] Three acute phase SAA isoforms 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 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). Three A-SAA genes have also been identified in humans [cite journal |author=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=Scand. J. Immunol. |volume=34 |issue=4 |pages=471–82 |year=1991 |pmid=1656519 |doi= |url=] , although the third gene, "SAA3", is believed to represent a pseudogene that does not generate messenger RNA or protein. [cite journal |author=Kluve-Beckerman B, Drumm ML, Benson MD |title=Nonexpression of the human serum amyloid A three (SAA3) gene |journal=DNA Cell Biol. |volume=10 |issue=9 |pages=651–61 |year=1991 |pmid=1755958 |doi= |url=]

Constitutive serum amyloid A proteins

A fourth SAA (SAA4) was identified in humans and is expressed constitutively in the liver thus is defined as a constitutive SAA (C-SAA). [cite journal |author=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 |year=1993 |pmid=7686132 |doi=10.1006/geno.1993.1209 |url=] A similar protein has since been identified in the mouse that is now also called SAA4; it had originally been designated SAA5. [cite journal |author=de Beer MC, Kindy MS, Lane WS, de Beer FC |title=Mouse serum amyloid A protein (SAA5) structure and expression |journal=J. Biol. Chem. |volume=269 |issue=6 |pages=4661–7 |year=1994 |pmid=8308037 |doi= |url=http://www.jbc.org/cgi/pmidlookup?view=long&pmid=8308037] [cite journal |author=de Beer MC, de Beer FC, Gerardot CJ, "et al" |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 |year=1996 |pmid=8661036 |doi=10.1006/geno.1996.0253 |url=]

References


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