The mRNA decapping complex is a protein complex in eukaryotic cells responsible for removal of the 5' cap

5' cap

The 5' cap is a specially altered nucleotide on the 5' end of precursor messenger RNA and some other primary RNA transcripts as found in eukaryotes. The process of 5' capping is vital to creating mature messenger RNA, which is then able to undergo translation...

. The core of the decapping complex is the Nudix family

Nudix family

The Nudix family is a protein family of phosphohydrolases. Using water-mediated catalysis they break a phosphate bond in their substrate to create two products. Nudix stands for Nucleoside Diphosphate linked to X...

 enzyme Dcp2

DCP2

mRNA-decapping enzyme 2 is a protein that in humans is encoded by the DCP2 gene.-Interactions:DCP2 has been shown to interact with DCP1A and UPF1.-Further reading:...

. 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

Helicase

Helicases are a class of enzymes vital to all living organisms. They are motor proteins that move directionally along a nucleic acid phosphodiester backbone, separating two annealed nucleic acid strands using energy derived from ATP hydrolysis.-Function:Many cellular processes Helicases are a...

 Dhh1, the exonuclease

Exonuclease

Exonucleases are enzymes that work by cleaving nucleotides one at a time from the end of a polynucleotide chain. A hydrolyzing reaction that breaks phosphodiester bonds at either the 3’ or the 5’ end occurs. Its close relative is the endonuclease, which cleaves phosphodiester bonds in the middle ...

 Xrn1, nonsense mediated decay

Nonsense mediated decay

Nonsense-mediated decay is a cellular mechanism of mRNA surveillance that functions to detect nonsense mutations and prevent the expression of truncated or erroneous proteins. Following transcription, precursor mRNA undergoes an assemblage of ribonucleoprotein components followed by regulatory...

 factors Upf1, Upf2, and Upf3, the LSm

LSm

In biology, LSm proteins are a family of RNA-binding proteins found in virtually every cellular organism. LSm is a contraction of 'like Sm', because the first identified members of the LSm protein family were the Sm proteins...

 complex, Pat1, and various other proteins. These proteins all localize to cytoplasmic structures called P-bodies

P-bodies

Processing bodies were first described in the scientific literature by Bashkirov et. al. in 1997, in which they describe "small granules… discrete, prominent foci" as the cytoplasmic location of the mouse exoribonuclease mXrn1p. It wasn’t until 2002 that a glimpse into the nature and importance of...

. 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

Immunoprecipitation

Immunoprecipitation is the technique of precipitating a protein antigen out of solution using an antibody that specifically binds to that particular protein. This process can be used to isolate and concentrate a particular protein from a sample containing many thousands of different proteins...

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