Nucleoside monophosphate (NMP) kinase that catalyzes the reversible transfer of the terminal phosphate group between nucleoside triphosphates and monophosphates. Has highest activity toward AMP, and weaker activity toward dAMP, CMP and dCMP. Also displays broad nucleoside diphosphate kinase activity. Involved in maintaining ciliary structure and function. AMP + ATP = 2 ADP a 2'-deoxyribonucleoside 5'-diphosphate + ATP = a 2'-deoxyribonucleoside 5'-triphosphate + ADP a ribonucleoside 5'-diphosphate + ATP = a ribonucleoside 5'-triphosphate + ADP Detected along the full length of sperm flagellum, where it colocalizes with alpha-tubulin. Mutant mice present pathological signs characteristic of primary ciliary dyskinesia (PCD), including high prevalence of microtubular defects, significantly decreased ciliary beat frequency, hydrocephalus, abnormal spermatogenesis, mucus accumulation in the paranasal passages, and exacerbated respiratory responses upon allergen challenge. This phenotype arose serendipitously in the process of generating transgenic mice harboring a heme oxygenase 1 construct, due to the serendipitous disruption of Ak7 locus by the transgene insertion event (PubMed:18776131). Mutant testes reveal the absence of flagellum structures, compared with those from control littermates. In mutant testes, nearly all sperm heads are attached to cytoplasmic mass and not prolonged by flagellar structures, such as mitochondrial sheath, fibrous sheath and axoneme. In mutant epididymes, very few sperm structures are observed. The rare sperm flagellum observed show an absence of the central pair of microtubules (PubMed:29365104). In the central section; belongs to the adenylate kinase family. In the C-terminal section; belongs to the dpy-30 family.