Ribokinase catalyses the phosphorylation of ribose to ribose-5-phosphate using ATP. The reaction is the first step in ribose metabolism and acts partly to trap ribose within the cell after uptake. Phosphorylation also prepares the sugar for use in the synthesis of nucleotides, histidine and for entry into the pentose phosphate pathway. Ribokinase is apart of the Ribokinase superfamily (also known as the PfkB family) alongside fructokinase and adenosine kinase which share two conserved motifs at the N and C terminus.
Defined by 4 residues: ALA:A-252ALA:A-253GLY:A-254ASP:A-255