mRNA juxtacap sequences govern mRNA translation and stability

Here we utilize a highly precise transcription-start site (TSS) mapping method to assess the relative contributions of the first transcribed nucleotides and modifications (the "juxtacap") to mRNA stability and translation. We find that several functionally relevant juxtacaps exist, and the presence of m6Am regulates the effect of adenosine juxtacaps. Overall design: Development of 5'UTR SLAM-seq for assaying half-lives, and 5'UTR polysome profiling to measure the mean ribosome load (MRL; equivalent to translational efficiency).