AK2

Adenylate kinase 2 (AK2) is an enzyme that in humans is encoded by the AK2 gene. This enzyme plays a crucial role in cellular energy homeostasis, nucleotide metabolism, and mitochondrial function. AK2 catalyzes the reversible transfer of the terminal phosphate group between ATP and AMP. This reaction is critical in maintaining the cell's energy balance, especially in tissues with high energy demands.

Function

AK2 is predominantly located in the mitochondria, where it facilitates the homeostasis of adenine nucleotides within the cell. By converting two molecules of ADP into one ATP and one AMP, AK2 helps in the maintenance of a high ATP to ADP ratio, a critical factor for the energy-consuming reactions within the cell. This enzyme is also involved in the regulation of the mitochondrial permeability transition pore, which is essential for apoptotic processes, thereby linking AK2 to cell survival and death mechanisms.

Clinical Significance

Mutations in the AK2 gene have been associated with a rare genetic disorder known as Reticular Dysgenesis. This condition is characterized by severe combined immunodeficiency (SCID), agranulocytosis, and sensorineural deafness. Patients with Reticular Dysgenesis have mutations that lead to the loss of AK2 function, which is critical for the development and function of lymphocytes and neutrophils. The absence of AK2 disrupts mitochondrial integrity, leading to impaired cellular energy metabolism and increased susceptibility to apoptosis, underlying the severe immunodeficiency observed in these patients.

Genetic

The AK2 gene is located on the short (p) arm of chromosome 1 at position 22.1, spanning approximately 12 kilobases. The gene consists of several exons that encode the AK2 protein. Genetic studies have identified various mutations in the AK2 gene that result in the loss of enzyme activity, which is directly linked to the pathogenesis of Reticular Dysgenesis.

See Also

• Adenylate kinase
• Mitochondria
• Reticular Dysgenesis
• Severe combined immunodeficiency