SAA2: Serum Amyloid A2 - Acute Phase Protein and Amyloidosis Marker
Comprehensive genomic and proteomic analysis of SAA2, a key acute-phase reactant involved in amyloid A amyloidosis and inflammation.
Gene Information Card
| Symbol | SAA2 |
|---|---|
| Full Name | Serum Amyloid A2 |
| Gene Type | protein-coding |
| Chromosomal Location | 11p15.1 |
| NCBI Gene ID | 6289 ncbi.nlm.nih.gov/gene/6289 |
| Ensembl ID | ENSG00000134339 |
| UniProt ID | P0DJI9 |
| OMIM ID | 104751 |
| HGNC ID | 10515 |
| Aliases | SAA2, SAA, SAA2.1, SAA2.2 |
Description
SAA2 (Serum Amyloid A2) encodes a member of the serum amyloid A (SAA) family, a major acute-phase protein predominantly synthesized by the liver in response to inflammation, infection, or tissue injury. SAA2 is a precursor to amyloid A (AA) fibrils, which deposit in tissues causing secondary (AA) amyloidosis. The protein is involved in lipid metabolism, chemotaxis, and modulation of the immune response. SAA2 is highly conserved and shares sequence similarity with SAA1.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Amyloidosis, AA type (secondary amyloidosis) | Deposition of SAA2-derived amyloid fibrils in tissues, particularly kidney, liver, and spleen, leading to organ dysfunction. Chronic inflammation drives sustained high SAA2 production, promoting fibrillogenesis. | ClinVar, OMIM #104751 |
| Familial Mediterranean Fever (FMF) | Recurrent inflammatory attacks elevate SAA2 levels, increasing risk of AA amyloidosis. Mutations in MEFV gene cause FMF, with SAA2 as a downstream effector. | OMIM #249100, ClinVar |
| Rheumatoid Arthritis | Chronic inflammation in RA leads to persistently high SAA2 levels, contributing to AA amyloidosis risk. | NCBI Gene, PubMed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 1245.3 | High |
| Adipose tissue | 45.2 | Medium |
| Lung | 12.1 | Low |
| Kidney | 8.5 | Low |
| Spleen | 6.3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 (hepatocellular carcinoma) | 156.2 | Liver-derived, high baseline expression |
| THP-1 (monocytic leukemia) | 23.4 | Induced by LPS/IL-1β |
| A549 (lung carcinoma) | 5.1 | Low constitutive expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.175G>A (p.Gly59Arg) | Missense | <0.1% | Reported in AA amyloidosis; may alter fibril formation propensity |
| c.202C>T (p.Arg68Cys) | Missense | <0.1% | Associated with reduced protein stability; ClinVar uncertain significance |
| c.301A>G (p.Thr101Ala) | Missense | 0.2% | Likely benign; population polymorphism |
Mutation functional classification
Loss of Function (LOF)
No well-characterized loss-of-function mutations; SAA2 is essential for acute-phase response.
Gain of Function (GOF)
Missense variants (e.g., p.Gly59Arg) may enhance amyloidogenic propensity, acting as gain-of-function in fibril formation.
Dominant Negative (DN)
Not described for SAA2.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Acute phase response (Reactome: R-HSA-6783783)
• Interleukin-6 signaling (Reactome: R-HSA-1059683)
• Amyloid fiber formation (Reactome: R-HSA-977225)
Protein Summary
Serum amyloid A2 (SAA2) is a 122-amino acid apolipoprotein (12.5 kDa) predominantly secreted by hepatocytes. It circulates bound to high-density lipoproteins (HDL) and is rapidly induced during acute inflammation (up to 1000-fold). SAA2 has a conserved N-terminal region critical for amyloid fibril formation. The protein modulates cholesterol transport, recruits immune cells, and activates Toll-like receptors (TLR2/TLR4). Under chronic inflammation, SAA2 misfolds into β-sheet-rich amyloid fibrils, leading to AA amyloidosis. UniProt ID: P0DJI9.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SAA2 Knockout HEK293 Cell Line | EDJ-KQ50605 | Human | 6289 | Details Get a Quote |
| SAA2-SAA4 Knockout HEK293 Cell Line | EDJ-KQ52485 | Human | 100528017 | Details Get a Quote |
| SAA2 Knockout HeLa Cell Line | EDJ-KQ54385 | Human | 6289 | Details Get a Quote |
| SAA2-SAA4 Knockout HeLa Cell Line | EDJ-KQ60948 | Human | 100528017 | Details Get a Quote |
| SAA2 Knockout A-549 Cell Line | EDJ-KQ62878 | Human | 6289 | Details Get a Quote |
| SAA2-SAA4 Knockout A-549 Cell Line | EDJ-KQ69423 | Human | 100528017 | Details Get a Quote |
| SAA2 Knockout HCT 116 Cell Line | EDJ-KQ71344 | Human | 6289 | Details Get a Quote |
| SAA2-SAA4 Knockout HCT 116 Cell Line | EDJ-KQ77774 | Human | 100528017 | Details Get a Quote |
