RNA recognition motif (RRM) found in the GW182 family proteins
This subfamily corresponds to the RRM of the GW182 family which includes three paralogs of TNRC6 (GW182-related) proteins comprising GW182/TNGW1, TNRC6B (containing three isoforms) and TNRC6C in mammal, a single Drosophila ortholog (dGW182, also called Gawky) and two Caenorhabditis elegans orthologs AIN-1 and AIN-2, which contain multiple miRNA-binding sites and have important functions in miRNA-mediated translational repression, as well as mRNA degradation in Metazoa. The GW182 family proteins directly interact with Argonaute (Ago) proteins, and thus function as downstream effectors in the miRNA pathway, responsible for inhibition of translation and acceleration of mRNA decay. Members in this family are characterized by an abnormally high content of glycine/tryptophan (G/W) repeats, one or more glutamine (Q)-rich motifs, and a C-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). The only exception is the worm protein that does not contain a recognizable RRM domain. The GW182 family proteins are recruited to miRNA targets through an interaction between their N-terminal domain and an Argonaute protein. Then they promote translational repression and/or degradation of miRNA targets through their C-terminal silencing domain.