AK5,7,8,9 phosphorylates (d)NMPs to (d)NDPs

Adenylate kinases (AKs) are nucleoside monophosphate kinases, which catalyze the phosphorylation of AMP by using ATP or GTP as phosphate donors. AKs are thus involved in maintaining the homeostasis of cellular nucleotides. CMP, dCMP and dAMP are other substrates phosphorylated with less efficiency by AKs. Cytosolic adenylate kinases 5, 7, 8 and 9 (AK5, 7, 8 and 9) catalyze the reversible phosphorylation of (d)AMP and (d)CMP with ATP to form (d)ADP and (d)CDP, respectively, and ADP. When GTP is the phosphate donor, only AMP and CMP are efficiently phosphorylated (Panayiotou et al. 2011, Amiri et al. 2013). In the body AK5 expression was observed only in brain of nine tissues tested by Northern blotting (Van Rompay et al. 1999). AK5 is inferred to occur as a dimer from unpublished crystallographic data obtained for the catalytically active carboxyterminal third of the protein (PDB 2BWJ).

腺苷酸激酶（AKs）是核苷单磷酸激酶，它们通过利用ATP或GTP作为磷酸供体来催化AMP的磷酸化。因此，AKs在维持细胞核苷酸稳态中发挥着重要作用。CMP、dCMP和dAMP是其他由AKs以较低效率磷酸化的底物。细胞质腺苷酸激酶5、7、8和9（AK5、7、8和9）催化（d）AMP和（d）CMP与ATP的可逆磷酸化，分别形成（d）ADP和（d）CDP，以及ADP。当GTP作为磷酸供体时，只有AMP和CMP能够被有效磷酸化（Panayiotou等，2011，Amiri等，2013）。在体内，通过Northern blotting检测发现AK5的表达仅限于九种组织中的一种——大脑（Van Rompay等，1999）。根据未发表的晶体学数据，AK5被推断为以二聚体的形式存在，这些数据来自蛋白质催化活性羧基末端第三部分的晶体结构（PDB 2BWJ）。