FCN3

Protein identityUniProt · HPA

UniProt accession

O75636

Gene

FCN3

Ensembl

ENSG00000142748

Chromosome

1

Canonical length

299 aa

Protein class

Disease related genes, Human disease related genes, Plasma proteins, Predicted secreted proteins

Secretome location

Secreted to blood

Quaternary structure

Homotrimer

OverviewNCBI Gene

Ficolins are a group of proteins which consist of a collagen-like domain and a fibrinogen-like domain. In human serum, there are two types of ficolins, both of which have lectin activity. The protein encoded by this gene is a thermolabile beta-2-macroglycoprotein found in all human serum and is a member of the ficolin/opsonin p35 lectin family. The protein, which was initially identified based on its reactivity with sera from patients with systemic lupus erythematosus, has been shown to have a calcium-independent lectin activity. The protein can activate the complement pathway in association with MASPs and sMAP, thereby aiding in host defense through the activation of the lectin pathway. Alternative splicing occurs at this locus and two variants, each encoding a distinct isoform, have been identified. [provided by RefSeq, Jul 2008]

Canonical amino-acid sequenceUniProt

299 residues, UniProt reviewed canonical sequence.

>O75636|FCN3
     1  MDLLWILPSL WLLLLGGPAC LKTQEHPSCP GPRELEASKV VLLPSCPGAP GSPGEKGAPG
    61  PQGPPGPPGK MGPKGEPGDP VNLLRCQEGP RNCRELLSQG ATLSGWYHLC LPEGRALPVF
   121  CDMDTEGGGW LVFQRRQDGS VDFFRSWSSY RAGFGNQESE FWLGNENLHQ LTLQGNWELR
   181  VELEDFNGNR TFAHYATFRL LGEVDHYQLA LGKFSEGTAG DSLSLHSGRP FTTYDADHDS
   241  SNSNCAVIVH GAWWYASCYR SNLNGRYAVS EAAAHKYGID WASGRGVGHP YRRVRMMLR

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against FCN3 can act on the native protein depends on physical access: surface and secreted proteins are reachable by circulating antibodies, intracellular proteins usually are not.

Antibody reachability

Cell surface

Secreted

No

Transmembrane segments

0

Mean surface accessibility (rSASA)

0.37

Highest tissue expression

688 nTPM

Expression across tissuesHPA

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about FCN3.

Disease | AllUniProt

Conditions FCN3 is implicated in, by any mechanism.

• Ficolin 3 deficiency (FCN3D) MIM:613860

Disease | GeneticClinVar

5 pathogenic / likely-pathogenic of 80 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

• Immunodeficiency due to ficolin3 deficiency

ReferencesPubMed · IEDB

Publications for FCN3 from three distinct lines of evidence, kept separate because they answer different questions: whether antibodies are directed at the protein, whether a B-cell epitope has been mapped on it, and whether a T-cell epitope has. Each is labelled with its source.

Sources: PubMed — antigen-level antibody evidence from a custom retrieval. Records matching a controlled set of autoantibody terms (the MeSH descriptors Autoantibodies and Autoantigens, with title and abstract term variants) were obtained through NCBI E-utilities, and their titles and abstracts parsed for constructions that direct an antibody at a named protein rather than for co-occurrence. Captured names were resolved against UniProt nomenclature and each antigen adjudicated individually against the source text. Bibliographic records from PubMed and MeSH, U.S. National Library of Medicine; citation metrics from NIH iCite (Hutchins et al., PLoS Biology 2016). Titles link to PubMed; abstracts are not reproduced here. The NLM does not endorse this analysis.

Genetic constraint and essentialitygnomAD · DepMap

Does the body need this protein intact? Low LOEUF or a strong DepMap dependency means loss or blockade of the protein is likely to be felt.

gnomAD LOEUF (loss-of-function intolerance)

0.9

gnomAD pLI

0

gnomAD missense Z

0.42

DepMap mean gene effect

-0.02

DepMap dependency class

selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 3% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

• cell surface pattern recognition receptor signaling pathway
• complement activation
• complement activation, lectin pathway
• defense response to virus
• host-mediated suppression of symbiont invasion
• positive regulation of opsonization
• proteolysis
• recognition of apoptotic cell
• negative regulation of RNA biosynthetic process

Molecular functions

• antigen binding
• carbohydrate binding
• carbohydrate derivative binding
• metal ion binding
• pattern recognition receptor activity
• signaling receptor binding

Cellular components

• blood microparticle
• collagen trimer
• external side of plasma membrane
• extracellular region
• extracellular space
• serine-type endopeptidase complex
• symbiont cell surface

Protein domainsUniProt · Pfam · InterPro

• Fibrinogen, alpha/beta/gamma chain, C-terminal globular domain
• Fibrinogen, alpha/beta/gamma chain, C-terminal globular, subdomain 1
• Fibrinogen, conserved site
• Fibrinogen-like, C-terminal
• Fibrinogen C-terminal domain-containing protein
• Fibrinogen beta and gamma chains, C-terminal globular domain

KeywordsUniProt

• Calcium
• Collagen
• Complement activation lectin pathway
• Disulfide bond
• Glycoprotein
• Hydroxylation
• Immunity
• Innate immunity
• Lectin
• Metal-binding
• Repeat
• Secreted
• Signal

InteractionsUniProt · HPA

Protein binding partners of FCN3 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

• MASP1
• MASP2