Function: Decapping scavenger enzyme that catalyzes the cleavage of a residual cap structure following the degradation of mRNAs by 3'->5' exosome-mediated mRNA decay pathway. Hydrolyzes cap analog structures like 7-methylguanosine nucleoside triphosphate (m7GpppG) with up to 10 nucleotide substrates (small capped oligoribonucleotides) and specifically releases 5'-phosphorylated RNA fragments and 7-methylguanosine monophosphate (m7GMP). Cleaves cap analog structures like tri-methyl guanosine nucleoside triphosphate (m3(2,2,7)GpppG) with very poor efficiency. Does not hydrolyze unmethylated cap analog (GpppG) and shows no decapping activity on intact m7GpppG-capped mRNA molecules longer than 25 nucleotides. Does not hydrolyze 7-methylguanosine diphosphate (m7GDP) to m7GMP. May also play a role in the 5'->3 mRNA decay pathway; m7GDP, the downstream product released by the 5'->3' mRNA mediated decapping activity, may be also converted by DCPS to m7GMP. Binds to m7GpppG and strongly to m7GDP. Plays a role in first intron splicing of pre-mRNAs. Inhibits activation-induced cell death
By similarity.
Catalytic activity: A 5'-(N(7)-methyl 5'-triphosphoguanosine)-(mRNA) + H2O = N(7)-methylguanosine 5'-phosphate + a 5'-diphospho-(mRNA).
Enzyme regulation: The hydrolytic product 7-methylguanosine diphosphate (m7GDP) efficiently inhibits the decapping scavenger activity and acts as a competitive inhibitor in vitro. Inhibited by 2,4-diaminoquinazoline
By similarity.
Subunit structure: Homodimer. Associates with components of the exosome multienzyme ribonuclease complex, such as EXOSC3 and EXOSC4. Interacts with NDOR1
By similarity.
Subcellular location: Cytoplasm
By similarity. Nucleus
By similarity. Note: Predominantly localized in the nucleus. Nucleocytoplasmic shuttling protein that can transiently enter the cytoplasm in mammalian cells in a XPO1/CRM1-dependent manner
By similarity.
Domain: The C-terminal histidine triad (HIT) motif and the N-terminal domain are required for the decapping activity. The N-terminus is necessary but not sufficient for binding cap structures
By similarity.
Sequence similarities: Belongs to the HIT family.
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