Widespread and dynamic translation efficiency control during erythropoiesis. (A) Translation efficiency of 762 genes differentially regulated (empirical P < .05) during erythropoiesis. Heatmap displays mean row-centered log2 TE values at 0, 24, 33, and 48 hours of ex vivo culture. Letters A through G at the left designate clusters; example genes are listed at the right. (B) Top gene pathways (P < .05, Fisher’s exact test) identified among genes that are translationally downregulated (Cluster A, top panel) or upregulated (Cluster D, bottom panel) during terminal differentiation. (C) Validation of translational repression (top) and activation (bottom) of mRNAs from Clusters A and D during differentiation. (D) Upstream ORFs consistently suppress translation through the stages of erythropoiesis. (E) Translation efficiency of 20 uORF and downstream CDS pairs differentially regulated (empirical P < .05) during erythropoiesis. Heatmaps display mean row-centered log2 TE values. (F-G) Ribosome and RNA profiling of Tal1 (F) and Ergic2 (G). Tal1 is translationally induced with differentiation and has a concordant uORF translation pattern, whereas Ergic2 is repressed and shows an opposite uORF pattern. Gene models with CDS (blue), UTR (green), and uORF (pink) regions are shown at the bottom.