NM23-H1 [NM301]

Non-metastatic protein 23 homolog 1; also NDKA or NM23-H1 is a 19‑20 kDa member of the NDK family of enzymes. NM23-H1 is ubiquitous in expression and performs multiple functions. It forms disulfide-linked homohexamers, and heterohexamers with NM23-H2, generating a nucleoside diphosphate kinase that catalyzes a phosphoryl transfer from ATP to a nucleoside diphosphate. It also shows His and Ser/Thr protein kinase activity and forms covalent linkages with molecules diverse as p53 and STRAP. It is found both intracellularly and in blood at ng/mL concentrations. Human NM23-H1 is 152 amino acids (aa) in length, contains one NDP kinase domain (aa 5‑134), and shows acetylation at Ala2 and Lys56, plus phosphorylation at Tyr52, Thr94, Ser122, and Ser125. Human NM23-H1 shares 89% aa identity with human 17‑18 kDa NM23-H2. The NM23 gene, a potential suppressor of metastasis, was originally identified by differential hybridization between two murine melanoma sub-lines, one with a high and the second with a low metastatic capacity. Highly metastatic sub-lines exhibit much lower levels of nm23 than less metastatic cells.