ThTPase is a soluble cytosolic enzyme which converts thiamine triphosphate (ThTP) to thiamine diphosphate. This catalytic activity depends on a divalent metal cofactor, for example Mg++. ThTPase regulates the intracellular concentration of ThTP, maintaining it at a low concentration in vivo. ThTP acts as a messenger in cell signaling in response to cellular stress, and in addition, can phosphorylate proteins in certain tissues. There is another class of membrane-associated enzymes in animal tissues which also convert ThTP to thiamine diphosphate, however they do not belong to this subgroup. This subgroup belongs to the CYTH/triphosphate tunnel metalloenzyme (TTM)-like superfamily, whose enzymes have a unique active site located within an eight-stranded beta barrel.