A quantitative map of human primary microRNA processing sites

•This study provides a quantitative map of 1,816 human pri-miRNA processing sites •Only 758 are confidently processed, while the majority non-canonical or false entries •We uncover atypical events such as alternative, nick, and inverse •SRSF3 is broad-acting cofactor modulating canonical pri-miRNAs Maturation microRNA (miRNA) initiated by DROSHA that cleaves primary transcript (pri-miRNA). More than 1,800 miRNA loci annotated in humans, but it remains largely unknown whether at which cleaved DROSHA. Here, we performed vitro on full set (miRBase version 21) followed sequencing. This comprehensive profiling enabled us to classify miRNAs basis dependence their cleavage with respective efficiency measures. Only processed DROSHA, may be entries. Analyses DROSHA-dependent show key cis-elements for processing. We observe widespread alternative unproductive “nick” “inverse” SRSF3 auxiliary factor suppressing The data methods developed this will allow systematic analyses regulation.