Identification of translated small open reading frames in lymphocytes

Open reading frames (ORFs) are the genomic DNA sequences that have the potential to be translated. Genome annotation pipelines dismiss translation products of small ORFs (smORFs) of less than 100 codons (<300 nucleotides) as being unlikely to have a biological function. In this study, we systematically characterized smORFs in mouse B and T cells under different conditions and predicted a total of 5744 unique actively translated smORFs. We then extended our analysis to ORFs of 101-200 codons in length and predicted 945 of such longer translation products. Additionally, our results have suggested the existence of candidate secreted micropeptides. Furthermore, verifying their existence and identifying their functions will be essential and potentially lead to useful applications. Peripheral lymph nodes were isolated from 5 biological replicates of control C57BL/6 mice (Zfp36l1 floxed/floxed without Cre). Each sample was split to generate Ribosome profiling and total RNA-seq libraries. Ribosome profiling data is submitted here; the corresponding total RNA-seq datasets are available in GSE146073.