The crystal structure of the human Drosha ribonuclease enzyme in complex with two C-terminal helices of the DGCR8 protein. Drosha is shown with its two ribonuclease III domains in blue and orange, its double-stranded RNA binding domain in yellow, and the remainder of the protein, including two bound zinc ions (spheres) in gray. DGCR8 helices are shown in green. (Note: DGCR8 is also known as Pasha, or Partner of Drosha, in flies and worms.) Together, Drosha and DGCR8 form the Microprocessor complex, responsible for the processing of primary microRNA to pre-miRNA in the nucleus of almost all animal cells, the first step for producing endogenously derived miRNA involved in RNA interference. Rendered using PyMol from PDB ID 5A16.