Factor IX

F9
Identifiers
Aliases	F9, F9 p22, FIX, HEMB, P19, PTC, THPH8, coagulation factor IX, Blood coagulation factor IX, Christmas Factor
External IDs	OMIM: 300746; MGI: 88384; GeneCards: F9
Available structures
PDB	Ortholog search: PDBe RCSB
List of PDB id codes
	1CFH, 1CFI, 1EDM, 1IXA, 1MGX, 1NL0, 1RFN, 2WPH, 2WPI, 2WPJ, 2WPK, 2WPL, 2WPM, 3KCG, 3LC3, 3LC5, 4YZU, 4Z0K, 4ZAE, 4WM0, 4WMA, 4WMI, 4WMK, 4WN2, 4WNH, 5EGM, 5JBC, 5JB9, 5JBB, 5JB8, 5JBA
Enzyme activity
Gene location (Human)
Chr.	X chromosome (human)
End	139,563,459 bp
Gene location (Mouse)
Chr.	X chromosome (mouse)
End	59,076,119 bp
RNA expression pattern
	Top expressed in
	right lobe of liver; ; secondary oocyte; ; gonad; ; pancreatic ductal cell; ; skin of thigh; ; kidney; ; blood; ; human musculoskeletal system; ; muscular system; ; muscle;
	Top expressed in
	left lobe of liver; ; lumbar spinal ganglion; ; gallbladder; ; sexually immature organism; ; thoracic diaphragm; ; medial head of gastrocnemius muscle; ; dentate gyrus; ; nucleus of stria terminalis; ; piriform cortex; ; jejunum;
	More reference expression data
	More reference expression data
Gene ontology
Molecular function	endopeptidase activity; metal ion binding; peptidase activity; serine-type peptidase activity; hydrolase activity; calcium ion binding; serine-type endopeptidase activity; protein binding;
Cellular component	endoplasmic reticulum lumen; plasma membrane; Golgi lumen; extracellular exosome; extracellular region; extracellular space; collagen-containing extracellular matrix;
Biological process	hemostasis; blood coagulation, intrinsic pathway; zymogen activation; endoplasmic reticulum to Golgi vesicle-mediated transport; signal peptide processing; blood coagulation, extrinsic pathway; peptidyl-glutamic acid carboxylation; proteolysis; blood coagulation;
	Sources:Amigo / QuickGO
Orthologs
Databases	NCBI: entry; OMA: entry
	2158
	14071
	ENSG00000101981
	ENSMUSG00000031138
	P00740
	P16294
	NM_000133; NM_001313913
	NM_007979; NM_001305797
	NP_000124; NP_001300842
	NP_001292726; NP_032005
	Wikidata
View/Edit Human	View/Edit Mouse

Factor IX (EC 3.4.21.22) is one of the serine proteases involved in coagulation; it belongs to peptidase family S1. Deficiency of this protein causes haemophilia B.

It was discovered in 1952 after a young boy named Stephen Christmas was found to be lacking this exact factor, leading to haemophilia. Coagulation factor IX is on the World Health Organization's List of Essential Medicines.