Fig. 3.

eIF4A2 selectively binds to purine-rich motifs within 5′UTRs. All figures use the groups of mRNAs bound by either eIF4A1 or eIF4A2 as depicted in the Venn diagram in Fig. 2a. a 6 nt rolling average GC content in the 5′UTR shows eIF4A1-bound mRNAs have increased GC content at 3′ end of the 5′UTR. b Motif enrichment analysis of eIF4A2-bound mRNAs compared to eIF4A1-bound mRNAs as controls was carried out for the first and last 50 nt of the 5′UTRs and coding sequences (CDS) using the MEME algorithm from the MEME Suite [57]. Shown are enriched motifs with associated probabilities. c eIF4A2-bound mRNAs have a higher frequency of purine-rich motifs (AAGA, AGAA, GAAA, GAGA, AGAG, GGAA, AAAA, GAAG) identified as targets of eIF4A clamping following chemical inhibition by RocA [37] in the 5′UTR and CDS. Cumulative frequency plots depicting frequencies of purine-rich motifs in 5′UTRs, CDSes, and 3′UTRs, respectively, of bound mRNAs. Significance calculated using Dunn’s test with Bonferroni’s correction. d eIF4A2-bound mRNAs have enrichment of purine-rich motifs directly upstream of the AUG start codon. The first and last 50 nt of 5′UTRs of mRNAs bound by either eIF4A1 or eIF4A2 were used in analysis of enrichment over all mRNAs identified in the RIP-Seq experiment. Significance calculated using Dunn’s test with Bonferroni’s correction