It is noteworthy that the interaction between Sbp1 and eIF4G1 is mediated by Pab1 on 5′UTRPab1. Using purified RNA-free proteins, we observed no direct interactions between eIF4G1 and Sbp1, and between eIF4G1 and the RGG domain of Sbp1 (Sbp1RGG) (Supplemental Fig. S7). Previously, Sbp1 was shown to interact with translation initiation factor eIF4G1 via its RGG domain by a GST-pulldown assay using overexpressed eIF4G1 in E. coli cell extracts (Rajyaguru et al. 2012). We reasoned that the observed interaction between Sbp1 and eIF4G1 under the described experimental condition is likely mediated by endogenous RNAs or a ternary protein.