Dcp1 is a small protein containing an EVH1 domain. The Dcp1-Dcp2 complex plays a critical step in mRNA degradation with the removal of the 50 cap structure. Dcp1 stimulates the activity of Dcp2 by promoting and/or stabilizing the closed complex. The interface of Dcp1 and Dcp2 is not fully conserved and in higher eukaryotes it requires an additional factor. The proline-rich sequence (PRS)-binding sites in Dcp1p indicates that it belongs to a novel class of EVH1 domains. Dcp1 has 2 prominent sites,one required for the function of the Dcp1p-Dcp2p complex, and the other, the PRS-binding site of EVH1 domains, a binding site for decapping regulatory proteins. It also has a conserved hydrophobic patch is shown to be critical for decapping. The EVH1 domains are part of the PH domain superamily.