DCP2

Dcp2 is a highly conserved cytoplasmic enzyme that catalyzes the removal of the 5' cap from mRNA, a key trigger for cytoplasmic mRNA decay. In eukaryotes, Dcp2 forms the catalytic core of the decapping machinery, typically in association with Dcp1 and a set of regulatory factors. The hydrolysis of the cap structure from m7GpppN to a cap fragment and a 5'-monophosphate RNA commits the transcript to degradation by 5'-3' exonucleases such as Xrn1.

Structure and interactions: Dcp2 possesses a catalytic Nudix-like domain that contains the conserved Nudix motif essential for activity, flanked by regulatory regions. Dcp2 activity is stimulated by Dcp1 and by decapping activators and scaffolds, including Edc proteins and Pat1-Lsm complexes in yeast and metazoans, which help recruit substrates and promote assembly of processing bodies where mRNA decay concentrates.

Localization and regulation: In many cells, decapping factors localize to cytoplasmic processing bodies (P-bodies). Dcp2 activity is modulated by protein interactions, post-translational modifications, and cellular conditions; phosphorylation and other regulatory inputs influence substrate selection and complex formation.

Biological role and evolution: Dcp2 is broadly conserved among eukaryotes and is central to cytoplasmic mRNA turnover and surveillance. It participates in multiple decay pathways, including nonsense-mediated decay coupled decapping, and its activity impacts transcript half-lives and gene expression. Loss or impairment of Dcp2 function generally leads to stabilization of uncapped transcripts and widespread changes in mRNA dynamics.