RNA triphosphatase

Sloan-Kettering - Molecular Biology: Stewart Shuman: "RNA triphosphatase hydrolyzes the gamma phosphate of mRNA. The triphosphatase component of the capping apparatus has diverged in structure and mechanism during the transition from fungal to metazoan species. The metazoan triphosphatases belong to a superfamily of phosphatases (which includes protein tyrosine phosphatases and dual-specificity protein phosphatases) that act via formation and hydrolysis of a cysteinyl phosphate intermediate; the reaction requires no metal cofactor. The yeast and poxvirus RNA triphosphatases comprise a novel family of metal-requiring phosphohydrolases that share several sequence motifs implicated in catalysis. "