Adenylate kinase 2 (AK2) belongs to the Adenylate kinase family that contains three isozymes: AK1, AK2 and AK3. Adenylate kinases are involved in regulating the adenine nucleotide composition within a cell by catalyzing the reversible transfer of phosphate groups among adenine nucleotides. Adenylate kinase2 (AK2) is expressed in mitochondrial intermembrane space. It may play a role in apoptosis. It has been demonstrated that in apoptotic cells AK2 was translocated into the cytosol concomitantly with cytochronme C. Mutations in this gene are the cause of reticular dysgenesis. These mutations result in absent or strongly decreased protein expression. It has been also established that AK2 is specifically expressed in the stria vascularis region of the inner ear, which provides an explanation of the sensorineural deafness in these individuals.