The MTG proteins have RNA-binding properties. A. RNA-binding assay using Sepharose-conjugated RNA homopolymers followed by Western Blotting shows that MTG8, MTG16 and MTGR1 exogenously expressed in COS cells bind to poly(G) and poly(U), while do not bind to poly(A), poly(C) and uncoupled Sepharose beads. FMRP, which we used as a positive control, shows similar RNA-binding properties. B. Binding specificity is shown both by the MTG inability to bind poly(U) after digestion with micrococcal nuclease (shown here for MTG16), and by the inability to bind poly(U) of two non-RNA-binding proteins, BSA (10 μg) and GFP (transiently expressed in COS cells). C. Poly(U)-binding at different concentrations of NaCl shows the strength of RNA interaction of the MTG proteins and the control RNA-binding protein FMRP. D) In vitro transcribed and translated (TnT) MTG proteins maintain the ability to bind poly(U).