Thymidine kinase 2, mitochondrial

Thymidine kinase 2, mitochondrial (TK2) is a protein that in humans is encoded by the TK2 gene. This protein is a crucial component of the nucleoside salvage pathway, which is particularly important in non-dividing cells where de novo synthesis of DNA precursors is absent.

Function

Thymidine kinase 2 is a mitochondrial matrix protein. It is responsible for the phosphorylation of several nucleosides, and is a key enzyme in the salvage pathway of pyrimidine metabolism. The salvage pathway is one of two pathways by which nucleotides are synthesized. In the salvage pathway, nucleotides are synthesized from intermediates in the degradative pathway for nucleotides.

Clinical significance

Mutations in the TK2 gene are associated with mitochondrial DNA depletion syndrome 2 (MTDPS2). This is a disorder of infancy or childhood characterized by severe muscular weakness, often with hypotonia and respiratory insufficiency. Other features may include anemia, pancreatitis, hepatomegaly, gastrointestinal dysfunction, and lactic acidosis.

See also

• Thymidine kinase
• Mitochondrial DNA depletion syndrome

External links

• TK2 gene at NCBI
• TK2 gene at Genetics Home Reference