Memebers of this superfamily share the structure of the N-terminal domain of the scavenger mRNA decapping enzyme (DcpS), involved in mRNA degradation via the 3' end decay pathway PMID:15068804. Here mRNA is degraded from the 3' end by the exosome complex following deadenylation with the resulting capped oligonucleotide, of ten nucleotides or fewer, being the substrate for this enzyme. DcpS exists as a dimer and each monomer is comprised of an N-terminal and a C-terminal region. The two N-termini form into a domain-swapped dimer and carry out substrate binding, cap dinucleotide, and hydrolysis PMID:16246173.