ADA
EC 3.5.4.4
プリンヌクレオチドの分解経路に属する。アデノシンの６位アミノ基を加水分解的に脱アミノし、イノシンとアンモニアを生じる。
腸、脾臓など高等生物の諸器官や微生物、ガン組織に広く存在する。高等生物のADAはアデノシンの他2-デオキシアデノシンを基質とする。
Adenosine deaminase
- Alternative name(s)
- Adenosine aminohydrolase
- Gene names
- ADA (ADA1)
- Function
- Catalyzes the hydrolytic deamination of adenosine and 2-deoxyadenosine. Plays an important role in purine metabolism and in adenosine homeostasis. Modulates signaling by extracellular adenosine, and so contributes indirectly to cellular signaling events. Acts as a positive regulator of T-cell coactivation, by binding DPP4. Its interaction with DPP4 regulates lymphocyte-epithelial cell adhesion. Ref.13
- Catalytic activity
- Adenosine + H2O = inosine + NH3. HAMAP-Rule MF_00540
- Cofactor
- Binds 1 zinc ion per subunit. Ref.18
- Subunit structure
- Interacts with DPP4 (extracellular domain). Ref.10 Ref.11 Ref.12 Ref.14
- Subcellular location
- Cell membrane; Peripheral membrane protein; Extracellular side. Cell junction. Cytoplasmic vesicle lumen. Cytoplasm By similarity.
- Note: Colocalized with DPP4 at the cell junction in lymphocyte-epithelial cell adhesion.
- Tissue specificity
- Found in all tissues, occurs in large amounts in T-lymphocytes and, at the time of weaning, in gastrointestinal tissues.
- Polymorphism
- There is a common allele, ADA*2, also known as the ADA 2 allozyme. It is associated with the reduced metabolism of adenosine to inosine. It specifically enhances deep sleep and slow-wave activity (SWA) during sleep. HAMAP-Rule MF_00540
- Involvement in disease
- Severe combined immunodeficiency autosomal recessive T-cell-negative/B-cell-negative/NK-cell-negative due to adenosine deaminase deficiency (ADASCID) [MIM:102700]: An autosomal recessive disorder accounting for about 50% of non-X-linked SCIDs. SCID refers to a genetically and clinically heterogeneous group of rare congenital disorders characterized by impairment of both humoral and cell-mediated immunity, leukopenia, and low or absent antibody levels. Patients with SCID present in infancy with recurrent, persistent infections by opportunistic organisms. The common characteristic of all types of SCID is absence of T-cell-mediated cellular immunity due to a defect in T-cell development. ADA deficiency has been diagnosed in chronically ill teenagers and adults (late or adult onset). Population and newborn screening programs have also identified several healthy individuals with normal immunity who have partial ADA deficiency.
Note: The disease is caused by mutations affecting the gene represented in this entry.
