Decapping metalloenzyme that catalyzes the cleavage of the cap structure on mRNAs (PubMed:21070968). Removes the 7-methyl guanine cap structure from mRNA molecules, yielding a 5'-phosphorylated mRNA fragment and 7m-GDP (PubMed:21070968). Necessary for the degradation of mRNAs, both in normal mRNA turnover and in nonsense-mediated mRNA decay (By similarity). Plays a role in replication-dependent histone mRNA degradation. Has higher activity towards mRNAs that lack a poly(A) tail (PubMed:21070968). Has no activity towards a cap structure lacking an RNA moiety (PubMed:21070968). The presence of a N(6)-methyladenosine methylation at the second transcribed position of mRNAs (N(6),2'-O-dimethyladenosine cap; m6A(m)) provides resistance to DCP2-mediated decapping (By similarity). Blocks autophagy in nutrient-rich conditions by repressing the expression of ATG-related genes through degradation of their transcripts (By similarity). a 5'-end (N(7)-methyl 5'-triphosphoguanosine)-ribonucleoside in mRNA + H2O = a 5'-end phospho-ribonucleoside in mRNA + 2 H(+) + N(7)-methyl-GDP Mn(2+) ion is required for highest activity. Can also utilize magnesium ions. Found in a mRNA decay complex with LSM1, LSM3, LSM4, EXOSC2, EXOSC4, EXOSC10, PARN, XRN1, CNOT6, UPF1, UPF2 and UPF3B. Forms a complex with DCP1A, EDC3, DDX6 and EDC4/HEDLS, within this complex directly interacts with EDC4/HEDLS. Interacts with DPC1B, UPF1, UPF2 and UPF3B. Associates with polysomes. Interacts (via N-terminus and C-terminus) with TRIM21 (via N-terminus and C-terminus). Interacts with LIMD1, WTIP and AJUBA. Interacts with DDX17 in an RNA-dependent manner. Interacts with ZC3HAV1. Interacts with APOBEC3G in an RNA-dependent manner. Interacts with ZFP36L1 (via N-terminus). Interacts with NBDY. Predominantly cytoplasmic, in processing bodies (PB) (By similarity). A minor amount is nuclear (By similarity). Strongly expressed in brain and testis. Weakly expressed in lung. Not detected in heart, liver, kidney and muscle (at protein level). Strongly expressed in brain, heart, liver at 14.5 and 16.5 dpc. Strongly expressed in brain at 20 dpc. Weakly expressed in heart and liver at 20 dpc (at protein level). Belongs to the Nudix hydrolase family. DCP2 subfamily.