Gene Summary: This gene encodes vitamin K-dependent coagulation factor IX that circulates in the blood as an inactive zymogen. This factor is converted to an active form by factor XIa, which excises the activation peptide and thus generates a heavy chain and a light chain held together by one or more disulfide bonds. The role of this activated factor IX in the blood coagulation cascade is to activate factor X to its active form through interactions with Ca+2 ions, membrane phospholipids, and factor VIII. Alterations of this gene, including point mutations, insertions and deletions, cause factor IX deficiency, which is a recessive X-linked disorder, also called hemophilia B or Christmas disease.General information above from NCBI
Catalytic activity: Selective cleavage of Arg-|-Ile bond in factor X to form factor Xa.
Subunit structure: Heterodimer of a light chain and a heavy chain; disulfide-linked.
Domain: Calcium binds to the gamma-carboxyglutamic acid (Gla) residues and, with stronger affinity, to another site, beyond the Gla domain.
Subcellular location: Secreted.
Tissue specificity: Synthesized primarily in the liver and secreted in plasma.
Post-translational: Activated by factor XIa, which excises the activation peptide.
The iron and 2-oxoglutarate dependent 3-hydroxylation of aspartate and asparagine is (R) stereospecific within EGF domains.
Involvement in disease: Hemophilia B (HEMB) [MIM:306900]: An X-linked blood coagulation disorder characterized by a permanent tendency to hemorrhage, due to factor IX deficiency. It is phenotypically similar to hemophilia A, but patients present with fewer symptoms. Many patients are asymptomatic until the hemostatic system is stressed by surgery or trauma. Note=The disease is caused by mutations affecting the gene represented in this entry.
Note=Mutations in position 43 (Oxford-3, San Dimas) and 46 (Cambridge) prevents cleavage of the propeptide, mutation in position 93 (Alabama) probably fails to bind to cell membranes, mutation in position 191 (Chapel-Hill) or in position 226 (Nagoya OR Hilo) prevent cleavage of the activation peptide.
Thrombophilia, X-linked, due to factor IX defect (THPH8) [MIM:300807]: A hemostatic disorder characterized by a tendency to thrombosis. Note=The disease is caused by mutations affecting the gene represented in this entry.
Sequence similarity: Belongs to the peptidase S1 family.
Contains 2 EGF-like domains.
Contains 1 Gla (gamma-carboxy-glutamate) domain.
Contains 1 peptidase S1 domain.
General information above from UniProt