Schematic of miRNA processing.
The preliminary miRNA (pre-miRNA) containing the mature 5’ (red) or 3’ (blue) strand is transported out of the nucleus by exportan5 in complex with RAN•GTP, and released into the cytoplasm. The pre-miRNA is cleaved by the endonuclease III, Dicer, to produce the mature duplex miRNA of ~22 bases per strand. The mature duplex miRNA is then loaded onto a argonaute (AGO) protein where it is unwound, the passenger strand is released, and the guide strand is arranged in the A-form conformation (modelled here as either or both the 5’ and 3’ strand is used as the guide strand). The target mRNA (lime green or magenta) is bound to the complex, resulting the suppression of its translation and protein synthesis. EXP5 (green) was modelled from PDB id:3A6P, Dicer (purple) was from PDB id:4NH5, and AGO (brown) was modelled from PDB id:4W5R.