Post-translational modifications of the RGG domain of Sbp1 were known to modulate its molecular interactions in the cell (Hsieh et al. 2007). In this study, we demonstrated that arginine methylation in the RGG repeats of Sbp1 compromised the binding of Sbp1 to Pab1. In contrast, the same post-translational modification has little effect on the binding of Sbp1 to the RNA (5′UTRPab1) in vitro. Results from our in vitro translation assay show that the methylation of the RGG domain abolishes the translation repression activity of Sbp1 on 5′UTRPab1.