Ficolin-2 (FCN2)
The protein contains 313 amino acids for an estimated molecular weight of 34001 Da.
May function in innate immunity through activation of the lectin complement pathway. Calcium-dependent and GlcNAc-binding lectin. Enhances phagocytosis of S.typhimurium by neutrophils, suggesting an opsonic effect via the collagen region. (updated: March 4, 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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No binding partner found
Biological Process
Complement activation
Complement activation, lectin pathway
Defense response to Gram-negative bacterium
Defense response to Gram-positive bacterium
Innate immune response
Opsonization
Recognition of apoptotic cell
The reference OMIM entry for this protein is 601624
Ficolin 2; fcn2
Collagen/fibrinogen domain-containing lectin 2 p35
Opsonin p35
CLONING
Matsushita et al. (1996) reported the cloning and characterization of P35, a human lectin with collagen and fibrinogen domains. The P35 gene encodes ficolin-2 (FCN2). Endo et al. (1996) isolated genomic clones for P35 and a related gene shown to be identical to ficolin-1 (FCN1; 601252).GENE STRUCTURE
Hummelshoj et al. (2005) noted that the FCN2 gene contains 8 exons.MAPPING
Endo et al. (1996) mapped the FCN2 gene to chromosome 9q34 by fluorescence in situ hybridization.MOLECULAR GENETICS
Serum concentration of ficolin-2 varies considerably in healthy individuals. Hummelshoj et al. (2005) sequenced the promoter region, exons, and intron-exon boundaries of FCN2 in 157 Danish Caucasians, and measured ficolin-2 concentrations in serum and N-acetylglucosamine (GlcNAc) binding. FCN2 promoter polymorphisms were associated with marked changes in the ficolin-2 serum concentration, whereas 2 nonsynonymous SNPs (dbSNP rs17549193 and dbSNP rs7851696) clustered in exon 8 encoding the fibrinogen-like domain were associated with decreased and increased GlcNAc binding, respectively. Hummelshoj et al. (2005) suggested that functional polymorphic sites may regulate both the expression and function of ficolin-2.EVOLUTION
Endo et al. (2012) noted that human FCN1 is the ortholog of mouse Fcnb. Human FCN2 is closely related to mouse Fcna, but the genes appear to have evolved independently in each murine and primate lineage. The human FCN3 gene (604973) is a pseudogene in mouse.ANIMAL MODEL
Endo et al. (2012) noted that ficolins and mannose-binding lectin (MBL, or MBL2; 154545) are complexed with MBL-associated serine proteases (MASPs; see 600521). MBL is important in both autoimmune and infectious diseases. Endo et al. (2012) found that Fcna -/- mice and Fcna -/- Fcnb -/- mice lacked complement activation in sera due to the absence of complexes of Fcna and MASPs. Transnasal challenge of mice with a Streptococcus pneumoniae strain recognized by ficolins, but not by Mbl, resulted in reduced mouse survival and higher bacterial loads in Fcna -/-, Fcnb -/-, and Fcna -/- Fcnb -/- mice. Reconstitution of the Fcna-mediated lectin pathway with an Fcna-encoding plasmid prior to infection improved survival of Fcna -/- mice, but not Fcna -/- Fcnb -/- mice, indicating that both Fcna and Fcnb are essential in defense against S. pneumoniae. Endo et al. (2012) proposed that FCNA and FCNB have a crucial role in defense against pneumococcal infection through the lectin complement pathway. ... More on the omim web siteFeb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated
June 20, 2017: Protein entry updated
Automatic update: comparative model was added.
March 25, 2017: Additional information
No protein expression data in P. Mayeux work for FCN2
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 601624 was added.
Jan. 24, 2016: Protein entry updated
Automatic update: model status changed