Nucleoside diphosphate kinase and GTP-binding proteins. Possible mechanisms of coupling

Abstract

The results of numerous investigations during the last 20 years have shown that nucleoside diphosphate kinase (NDP kinase) is a multifunctional protein. In this paper, the current data are analyzed indicating that one of the possible mechanisms by which NDP kinase manifests its multifunctional role is its participation in the activation (or regulation) of heterotrimeric GTP-binding proteins (G proteins). We demonstrate that one of the NDP kinase isoforms dynamically interacts with the retinal rod G protein transducin (Gt) and phosphorylates its beta-subunit at histidine residue (His 266). It is also shown that it leads to the consecutive transfer of the phosphate group to the GDP in the active center of G protein alpha-subunit and G protein activation. The advantages of this mechanism are considered as compared to the classic G protein activation mechanism, GDP/GTP exchange.