Catalytic component of the decapping complex necessary for the degradation of mRNAs, both in normal mRNA turnover and in nonsense-mediated mRNA decay. Removes the 7-methyl guanine cap structure from mRNA molecules, yielding a 5'-phosphorylated mRNA fragment and 7m-GDP. Essential for postembryonic development, especially during the formation of the shoot apical meristem (SAM). 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 Inhibited by the product 7-methyl GDP. Homodimer. Catalytic component of the decapping complex. Interacts with DCP1, DCP5 and VCS. The localization to P-body is VCS-dependent. Expressed in seedlings, mostly in root tips, root hairs, and the vascular system. Also present in roots, leaves, stems, and flowers. Gradually accumulates upon germination. Lethal phenotype at the seedling cotyledon stage that are small and chlorotic, with disorganized veins, swollen root hairs, and altered epidermal cell morphology. Altered RNA decay. Belongs to the Nudix hydrolase family. DCP2 subfamily.