Nucleoside diphosphate kinase (NDP kinase, EC 2.7.4.6) is a ubiquitous enzyme that catalyzes phosphorylation of nucleoside 5'-diphosphate, with the exception of ADP, to the corresponding triphosphate, following a ping-pong mechanism, which includes the formation of a high-energy phosphohistidine intermediate. It has a broad specificity for phosphoryl donors and acceptors to maintain the balanced levels of nucleotide triphosphates in the cell. The structures of NDP kinases are highly conserved from Escherichia coli to human (43% identity) and they are believed to be a housekeeping enzymes for DNA and RNA synthesis. In addition, NDP kinases have been shown to have additional regulatory functions for growth and developmental control, signal transduction, transcription, activation of GTP-binding proteins, and tumour metastasis suppression. The recent information on the general properties, three-dimensional structure, quaternary structure, and the properties of the binding site of this enzyme are reported. (in Czech)