process can be thought of as a bucket brigade of ADK molecules that results in changes in local intracellular metabolic flux without apparent global changes in metabolite concentrations. This process is extremely important for overall homeostasis of the cell. Disease relevance Nucleoside diphosphate kinase deficiency Nucleoside diphosphate (NDP) kinase catalyzes in vivo ATP-dependent synthesis of ribo- and deoxyribonucleoside triphosphates. In mutated Escherichia coli that had a disrupted nucleoside diphosphate kinase, adenylate kinase performed dual enzymatic functions. ADK complements nucleoside diphosphate kinase deficiency. Nucleoside diphosphate (NDP) kinase catalyzes in vivo ATP-dependent synthesis of ribo- and deoxyribonucleoside triphosphates. In mutated Escherichia coli that had a disrupted nucleoside diphosphate kinase, adenylate kinase performed dual enzymatic functions. ADK complements nucleoside diphosphate kinase deficiency. AK1 and post-ischemic coronary reflow Knock out of AK1 disrupts the synchrony between inorganic phosphate and turnover at ATP-consuming sites and ATP synthesis sites. This reduces the energetic signal communication in the post-ischemic heart and precipitates inadequate coronary reflow following ischemia-reperfusion. ADK2 deficiency Adenylate Kinase 2 (AK2) deficiency in humans causes hematopoietic defects associated with sensorineural deafness. Reticular dysgenesis is an autosomal recessive form of human combined immunodeficiency. It is also characterized by an impaired lymphoid maturation and early differentiation arrest in the myeloid lineage. AK2 deficiency results in absent or a large decrease in the expression of proteins. AK2 is specifically expressed in the stria vascularis of the inner ear which indicates why individuals with an AK2 deficiency will have sensorineural deafness. Structural adaptations AK1 genetic ablation decreases tolerance to metabolic stress. AK1 deficiency induces fiber-type specific variation in groups of transcripts in glycolysis and mitochondrial metabolism. This supports muscle energy metabolism. Plastidial ADK deficiency in Arabidopsis thaliana Enhanced growth and elevated photosynthetic amino acid is associated with plastidial adenylate kinase deficiency in Arabidopsis thaliana. References External links Cellular respiration EC 2.7.4