Serum amyloid P-component (APCS)
The protein contains 223 amino acids for an estimated molecular weight of 25387 Da.
Can interact with DNA and histones and may scavenge nuclear material released from damaged circulating cells. May also function as a calcium-dependent lectin. (updated: April 1, 2015)
Protein identification was indicated in the following studies:
- Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
- Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
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| Variant | Description |
|---|---|
| a breast cancer sample; somatic mutation | |
| empty | |
| empty |
Biological Process
Acute-phase response
Amyloid fibril formation
Cellular protein metabolic process
Chaperone-mediated protein complex assembly
Complement activation, classical pathway
Innate immune response
Negative regulation by host of viral exo-alpha-sialidase activity
Negative regulation by host of viral glycoprotein metabolic process
Negative regulation by host of viral process
Negative regulation of acute inflammatory response
Negative regulation of exo-alpha-sialidase activity
Negative regulation of glycoprotein metabolic process
Negative regulation of monocyte differentiation
Negative regulation of viral entry into host cell
Negative regulation of viral process
Negative regulation of wound healing
Protein folding
The reference OMIM entry for this protein is 104770
Amyloid p component, serum; apcs
Serum amyloid p; sap
Pentraxin 2, short; ptx2
CLONING
Mantzouranis et al. (1985) isolated cDNA for the P component of human serum amyloid and determined the complete sequence of the precursor.MAPPING
Mantzouranis et al. (1985) assigned the APCS gene to chromosome 1 by studies of somatic cell hybrids. The gene is probably closely situated to that for C-reactive protein (CRP; 123260) with which it shows homology. By in situ hybridization, the assignment was made to segment 1q12-q23 (Floyd-Smith et al., 1985, 1986). Ionasescu et al. (1987) found a maximum lod score of 3.26 at theta = 0.05 for linkage of APCS with the Duffy blood group locus (110700). A RFLP marker of APCS was used. The linkage is consistent with the physical assignment of the 2 loci.GENETIC VARIABILITY
Woo et al. (1987) found a genetic marker for susceptibility to amyloidosis in juvenile arthritis: an 8.8-kb RFLP band determined by a polymorphic DNA site 5-prime to the SAP gene. Homozygosity for the alternative 5.6-kb band was found in none of 28 amyloid patients. Among 19 juvenile arthritic patients without amyloidosis, the distribution of the polymorphism was the same as that in the normal group. With a RFLP of the cloned mouse Sap gene, Whitehead et al. (1988) demonstrated that the gene maps to chromosome 1 in the same region specified by quantitative variation in Sap levels. They thought it might be significant that the same region includes CRP, SAP, and histone genes, all of which have products that interact with DNA.BIOCHEMICAL FEATURES
- Crystal Structure Lu et al. (2008) described the structural mechanism for pentraxin's binding to Fc-gamma-R and its functional activation of Fc-gamma-R-mediated phagocytosis and cytokine secretion. The complex structure between human SAP and Fc-gamma-RIIa (146790) showed a diagonally bound receptor on each SAP pentamer with both D1 and D2 domains of the receptor contacting the ridge helices from 2 SAP subunits. The 1:1 stoichiometry between SAP and Fc-gamma-RIIa implied the requirement for multivalent pathogen binding for receptor aggregation. Mutational and binding studies showed that pentraxins are diverse in their binding specificity for Fc-gamma-R isoforms but conserved in their recognition structure. The shared binding site for SAP and IgG caused competition for Fc-gamma-R binding and the inhibition of immune complex-mediated phagocytosis by soluble pentraxins. Lu et al. (2008) concluded that their results established antibody-like functions for pentraxins in the Fc-gamma-R pathway, suggested an evolutionary overlap between the innate and adaptive immune systems, and had therapeutic implications for autoimmune diseases.ANIMAL MODEL
Botto et al. (1997) generated mice with a targeted deletion of the SAP gene. Induction of reactive amyloidosis was retarded in these mice, demonstrating the participation of SAP in pathogenesis of amyloidosis in vivo and confirming that inhibition of SAP binding to amyloid fibrils is an attractive therapeutic target. Pepys et al. (2002) developed a drug that is a competitive inhibitor of SAP binding to amyloid fibrils. This palindromic compound also crosslinks and dimerizes SAP molecules, leading to their very rapid clearance by the liver and thus producing a marked depletion of circulating human SAP. Pepys et al. (2002) suggested that this mechanism of drug action potently removes SAP from human amyloid deposits in tissues and may provide a new therapeutic approach to both systemic amyl ... More on the omim web site
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 104770 was added.
Jan. 28, 2016: Protein entry updated
Automatic update: model status changed
Jan. 25, 2016: Protein entry updated
Automatic update: model status changed