The genomic location of PA clusters identified by PA-seq. (a) The genomic location of all PA clusters identified. The number of PA clusters for each subcategory is shown. (b) The location of PA clusters in protein-coding genes based on RefSeq annotation. (c) The number of PA clusters detected for protein-coding genes (left panel) and noncoding RNAs (right panel), respectively. The inset in each panel shows a representative locus with known annotations as well as PA clusters identified.