RNA-binding and decapping enzyme that catalyzes the cleavageof the cap structure of snoRNAs and mRNAs in a metal-dependent manner. Part of the U8 snoRNP complex that is required for the accumulation ofmature 5. 8S and 28S rRNA. Has diphosphatase activity and removes m7Gand/or m227G caps from U8 snoRNA and leaves a 5'monophosphate on theRNA. Catalyzes also the cleavage of the cap structure on mRNAs. Doesnot hydrolyze cap analog structures like 7-methylguanosine nucleosidetriphosphate (m7GpppG). Also hydrolysis m7G- and m227G U3-capped RNAsbut with less efficiencies. Has broad substrate specificity withmanganese or cobalt as cofactor and can act on various RNA species. Binds to the U8 snoRNA; metal is not required for RNA-binding. May playa role in the regulation of snoRNAs and mRNAs degradation. Acts also asa phosphatase; hydrolyzes the non-canonical purine nucleotides inosinediphosphate (IDP) and deoxyinosine diphosphate (dITP) as well asguanosine diphosphate (GDP), deoxyguanosine diphosphate (dGDP), xanthine diphosphate (XDP), inosine triphosphate (ITP) and deoxyinosinetriphosphate (ITP) to their respective monophosphate derivatives anddoes not distinguish between the deoxy- and ribose forms. The order of activity withdifferent substrates is IDP > dIDP >> GDP = dGDP > XDP = ITP = dITP. Binds strongly to GTP, ITP and XTP. Participates inthe hydrolysis of dIDP/IDP and probably excludes non-canonical purinesfrom RNA and DNA precursor pools, thus preventing their incorporationinto RNA and DNA and avoiding chromosomal lesions. Exhibits decapping activity towards NAD-capped RNAs and FAD-capped RNAs. Exhibits decapping activity towards dpCoA-cappedRNAs in vitro. [1-3]

MAGARRLELGEALALGSGWRHACHALLYAPDPGMLFGRIPLRYAILMQMRFDGRLGFPGGFVDTQDRSLEDGLNRELREELGEAAAAFRVERTDYRSSHVGSGPRVVAHFYAKRLTLEELLAVEAGATRAKDHGLEVLGLVRVPLYTLRDGVGGLPTFLENSFIGSAREQLLEALQDLGLLQSGSISGLKIPAHH