The supplemental information section provides detailed experimental data and analyses supporting the main findings of the study. It includes several figures and tables that address various aspects of circular RNAs (circRNAs) and their translation, including: 1. **Translation of CircRNAs**: - **Figure S1**: Shows the footprinting reads for non-ambiguous circRNAs and their comparison with junctions of the same exons. It also demonstrates the recognition and precipitation of circMblV5 protein using antibodies. - **Figure S2**: Analyzes polysome profiles of Drosophila S2 cells transfected with circRNAs, showing the distribution of RNA targets across different fractions of a polysome gradient. - **Figure S3**: Examines the RFP read phasing analysis for circRNAs, comparing samples with and without detergent, and assessing the translation and start/stop codons. - **Figure S4**: Demonstrates that a subset of circRNAs is associated with translating ribosomes, with comparisons of RFP backsplicing reads and validation of ribo-circRNAs. - **Figure S5**: Conducts computational analysis of ribo-circRNAs, including their length distribution, conservation, and domain enrichment. - **Figure S6**: Analyzes cORFs in mammals, comparing the number of predicted cORFs per circRNA in rat and mouse circRNAs, and examining the distribution of stop codons. - **Figure S7**: Shows that ribo-circRNAs have internal ribosome entry sites (IRES) sequences, with Western blot and luciferase assays demonstrating their translation potential. 2. **Tables**: - **Table S1**: Lists cORFs in *Drosophila melanogaster*. - **Table S2**: Provides a list of *Drosophila* ribo-circRNAs. - **Table S3**: Offers evolutionary conservation scores for *Drosophila* cORFs and ribo-circRNAs. - **Table S4**: Lists proteins domains found on ribo-circRNAs. - **Table S5**: Summarizes back-spliced reads detected in C2C12 ribosomal foot printing data. - **Table S6**: Summarizes back-spliced reads detected in rat samples ribosomal foot printing data. - **Table S7**: Lists the oligonucleotides used in the study. These supplementary materials provide comprehensive support for the experimental and computational analyses presented in the main text, enhancing the understanding of the role and characteristics of circRNAs in gene expression and translation.The supplemental information section provides detailed experimental data and analyses supporting the main findings of the study. It includes several figures and tables that address various aspects of circular RNAs (circRNAs) and their translation, including: 1. **Translation of CircRNAs**: - **Figure S1**: Shows the footprinting reads for non-ambiguous circRNAs and their comparison with junctions of the same exons. It also demonstrates the recognition and precipitation of circMblV5 protein using antibodies. - **Figure S2**: Analyzes polysome profiles of Drosophila S2 cells transfected with circRNAs, showing the distribution of RNA targets across different fractions of a polysome gradient. - **Figure S3**: Examines the RFP read phasing analysis for circRNAs, comparing samples with and without detergent, and assessing the translation and start/stop codons. - **Figure S4**: Demonstrates that a subset of circRNAs is associated with translating ribosomes, with comparisons of RFP backsplicing reads and validation of ribo-circRNAs. - **Figure S5**: Conducts computational analysis of ribo-circRNAs, including their length distribution, conservation, and domain enrichment. - **Figure S6**: Analyzes cORFs in mammals, comparing the number of predicted cORFs per circRNA in rat and mouse circRNAs, and examining the distribution of stop codons. - **Figure S7**: Shows that ribo-circRNAs have internal ribosome entry sites (IRES) sequences, with Western blot and luciferase assays demonstrating their translation potential. 2. **Tables**: - **Table S1**: Lists cORFs in *Drosophila melanogaster*. - **Table S2**: Provides a list of *Drosophila* ribo-circRNAs. - **Table S3**: Offers evolutionary conservation scores for *Drosophila* cORFs and ribo-circRNAs. - **Table S4**: Lists proteins domains found on ribo-circRNAs. - **Table S5**: Summarizes back-spliced reads detected in C2C12 ribosomal foot printing data. - **Table S6**: Summarizes back-spliced reads detected in rat samples ribosomal foot printing data. - **Table S7**: Lists the oligonucleotides used in the study. These supplementary materials provide comprehensive support for the experimental and computational analyses presented in the main text, enhancing the understanding of the role and characteristics of circRNAs in gene expression and translation.