ATP is the most common phosphoryl group donor for kinases. However, certain hyperthermophilic archaea such as Thermococcus litoralis and Pyrococcus furiosus utilize unusual ADP-dependent glucokinases and phosphofructokinases in their glycolytic pathways. These ADP-dependent kinases are homologous to each other but show no sequence similarity to any of the hitherto known ATP-dependent enzymes.
