Direct activation of guanine nucleotide binding proteins through a high-energy phosphate-transfer by nucleoside diphosphate-kinase

Abstract

An in , vitro study of phosphate-transfer, from the high-energy phosphates on the phosphoenzyme (enzyme-bound high-energy phosphate intermediate) of NDP-kinase to GDP on various guanine nucleotide binding proteins (G 1, elongation factor α 1, recombinant v- ras H p21 protein, transducin, Gi and Go), revealed that the GDP acts as a phosphate-acceptor, in the presence of divalent cations (Mg 2+ and Ca 2+). This finding suggests that via phosphate-transfer, NDP-kinase may be responsible for the direct activation of various guanine nucleotide binding proteins through phosphatetransfer by the enzyme.