Primary microRNA transcripts (pri-miRs) are cleaved by Microprocessor, a complex containing RNase III DROSHA and its cofactor DGCR8 []. DGCR8 functions as a molecular anchor necessary for the recognition of pri-miRNA at dsRNA-ssRNA junction and directs DROSHA to cleave 11 bp away form the junction to release hairpin-shaped pre-miRNAs that are subsequently cut by the cytoplasmic DICER to generate mature miRNAs [, ]. DGCR8 binds heme, and this binding activates DGCR8 to recognize pri-miRs by specifically binding the terminal loop near the 3' single-stranded segment [].
