BD Transduction Laboratories™ Purified Mouse Anti-Nm23

Nm23 is a potential metastasis suppressor protein whose expression is either reduced, altered (by mutation), or amplified in various types of metastatic carcinomas. Two human gene homologues, nm23-H1 and nm23-H2, encode 17 kDa proteins that are 90% identical. Nm23 proteins possess a nucleoside diphosphate kinase (NDPK) activity. This enzymatic activity catalyzes the synthesis of non-adenine-containing nucleoside triphosphates from nucleoside diphosphates via a phosphorylated enzyme intermediate. In addition, Nm23 inhibits differentiation, interacts with GTP-binding (GAP) proteins, autophosphorylates serine residues, and binds to DNA. The biochemical mechanisms by which Nm23 affects tumor metastatic potential have yet to be determined. In murine melanoma cell lines, serine 44 is the major site of autophosphorylation on Nm23-1. This acid-stable phosphorylation of Nm23 is inhibited in vitro by cAMP and in vivo by forskolin. These data indicate that this serine phosphorylation is regulated via some cAMP-dependent event in signal transduction. In addition, it has been shown that the Nm23-H2 protein is identical to the c-myc transcription factor PuF. This suggests that some of the cellular effects of Nm23 are mediated by its transcriptional regulatory function, while others are mediated by its NDPK activity.