GIGYF1/2 GYF domains directly interact with proline-rich sequences from GW182/TNRC6 proteins. (A) Schematic representation of human GIGYF1/2 and TNRC6A-C proteins. GIGYF1/2 contain a 4EHP-binding motif (4EHP-BM) and a Me31B/DDX6-binding motif (MBM) within their N-terminal region, as well as a central GYF domain. The conserved PPGL motifs of the TNRC6 proteins are located within their C-terminal silencing domains, which also contains a PAM motif and an RNA-recognition motif (RRM) domain. TNRC6A contains a classical nuclear localization signal (cNLS) between its Argonaute (AGO)-binding domain and ubiquitin-associated motif (UBA). The TNRC6 paralogs also contain Q-rich regions. (B) The PPGL motif is conserved in GW182/TNRC6A proteins in metazoa, and proline-rich sequences have been identified in RNA-binding proteins such as TTP and ZNF598. The PPGΦ motif is denoted by the black box, and the peptide sequences used in this study are indicated by the blue dashed box. For comparison, the PRS from ScBBP is also shown. The species abbreviations are as follows: Dm (Drosophila melanogaster), Dr (Danio rerio), Nv (Nematostella vectensis), Sc (Saccharomyces cerevisiae). (C,D) GST pull-downs using the recombinant His6-GIGYF1/2 GYF domain and GST-PRS sequences. GST only served as a negative control.
