Complement factor I

CFI
Available structures
PDB	Ortholog search: PDBe RCSB
List of PDB id codes
	2XRC
Identifiers
Aliases	CFI, AHUS3, ARMD13, C3BINA, C3b-INA, FI, IF, KAF, complement factor I
External IDs	OMIM: 217030; MGI: 105937; HomoloGene: 171; GeneCards: CFI; OMA:CFI - orthologs
Gene location (Human)
Chr.	Chromosome 4 (human)
End	109,802,179 bp
Gene location (Mouse)
Chr.	Chromosome 3 (mouse)
End	129,668,981 bp
RNA expression pattern
	Top expressed in
	germinal epithelium; ; parietal pleura; ; right lobe of liver; ; gallbladder; ; palpebral conjunctiva; ; visceral pleura; ; kidney tubule; ; human kidney; ; right adrenal cortex; ; caput epididymis;
	Top expressed in
	left lobe of liver; ; epithelium of stomach; ; pyloric antrum; ; gallbladder; ; mucous cell of stomach; ; fetal liver hematopoietic progenitor cell; ; migratory enteric neural crest cell; ; human fetus; ; endocardial cushion; ; yolk sac;
	More reference expression data
	n/a
Gene ontology
Molecular function	peptidase activity; hydrolase activity; serine-type peptidase activity; metal ion binding; serine-type endopeptidase activity; scavenger receptor activity; protein binding;
Cellular component	extracellular exosome; membrane; extracellular region; extracellular space;
Biological process	complement activation, classical pathway; regulation of complement activation; receptor-mediated endocytosis; proteolysis; immune system process; innate immune response; viral process; vesicle-mediated transport; endocytosis;
	Sources:Amigo / QuickGO
Orthologs
	3426
	12630
	ENSG00000205403
	ENSMUSG00000058952
	P05156; Q8WW88
	Q61129
	NM_000204; NM_001318057; NM_001331035
	NM_007686; NM_001329552
NP_000195; NP_001304986; NP_001317964; NP_001362207; NP_001362208;
	NP_001362209; NP_001362210; NP_001362211; NP_001362212; NP_001362213; NP_001304986.1
	NP_001316481; NP_031712
	Wikidata
View/Edit Human	View/Edit Mouse

Complement factor I, also known as C3b/C4b inactivator, is a protein that in humans is encoded by the CFI gene. Complement factor I (factor I) is a protein of the complement system, first isolated in 1966 in guinea pig serum,^[5] that regulates complement activation by cleaving cell-bound or fluid phase C3b and C4b.^[6] It is a soluble glycoprotein that circulates in human blood at an average concentration of 35 μg/mL.^[7]

^ ^a ^b ^c GRCh38: Ensembl release 89: ENSG00000205403 – Ensembl, May 2017
^ ^a ^b ^c GRCm38: Ensembl release 89: ENSMUSG00000058952 – Ensembl, May 2017
^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^ Nelson RA, Jensen J, Gigli I, Tamura N (March 1966). "Methods for the separation, purification and measurement of nine components of hemolytic complement in guinea-pig serum". Immunochemistry. 3 (2): 111–35. doi:10.1016/0019-2791(66)90292-8. PMID 5960883.
^ Lachmann PJ, Müller-Eberhard HJ (April 1968). "The demonstration in human serum of "conglutinogen-activating factor" and its effect on the third component of complement". Journal of Immunology. 100 (4): 691–8. doi:10.4049/jimmunol.100.4.691. PMID 5645214.
^ Nilsson SC, Sim RB, Lea SM, Fremeaux-Bacchi V, Blom AM (August 2011). "Complement factor I in health and disease". Molecular Immunology (Submitted manuscript). 48 (14): 1611–20. doi:10.1016/j.molimm.2011.04.004. PMID 21529951. S2CID 37521895.

[refGRCh38Ensembl-1] GRCh38: Ensembl release 89: ENSG00000205403 – Ensembl, May 2017

[refGRCm38Ensembl-2] GRCm38: Ensembl release 89: ENSMUSG00000058952 – Ensembl, May 2017

[3] "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.

[4] "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.

[5] Nelson RA, Jensen J, Gigli I, Tamura N (March 1966). "Methods for the separation, purification and measurement of nine components of hemolytic complement in guinea-pig serum". Immunochemistry. 3 (2): 111–35. doi:10.1016/0019-2791(66)90292-8. PMID 5960883.

[6] Lachmann PJ, Müller-Eberhard HJ (April 1968). "The demonstration in human serum of "conglutinogen-activating factor" and its effect on the third component of complement". Journal of Immunology. 100 (4): 691–8. doi:10.4049/jimmunol.100.4.691. PMID 5645214.

[7] Nilsson SC, Sim RB, Lea SM, Fremeaux-Bacchi V, Blom AM (August 2011). "Complement factor I in health and disease". Molecular Immunology (Submitted manuscript). 48 (14): 1611–20. doi:10.1016/j.molimm.2011.04.004. PMID 21529951. S2CID 37521895.

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