The mRNA decapping complex is a protein complex in eukaryotic cells responsible for removal of the 5' cap. The core of the decapping complex is the Nudix family enzyme Dcp2. Many other proteins assemble with Dcp2 to form a protein complex.
Yeast decapping complex
In yeast (S. cerevisiae), Dcp2 is joined by the decapping activator Dcp1, the helicase Dhh1, the exonuclease Xrn1, nonsense mediated decay factors Upf1, Upf2, and Upf3, the LSm complex, Pat1, and various other proteins. These proteins all localize to cytoplasmic structures called P-bodies. Notably in yeast there are no translation factors or ribosomal proteins inside P-bodies.
Metazoan decapping complex
Higher eukaryotes have slightly different members of the decapping complex. The enzyme Dcp2 is still the catalytic subunit along with Dcp1, Xrn1, Upf1-3, the LSm complex, and the Dhh1 ortholog Rck/p-54. Proteins unique to plants and mammals include the beta propeller protein Hedls and the enhancer of decapping Edc3. Structural details of the assembly of this complex are not known, only physical association by immunoprecipitation.
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