Figure 2: Mechanism of miR-1 biogenesis and common mechanism of action.
In case of humans, two discrete genes, MIR1–1 located on 20q13.333 and MIR1–2 located on 18q11.2 loci encode for a single mature miR-1. The initial stem loop or primary miR-1–1/miR-1–2 (pri-miR-1–1/pri-miR-1–2) were transcribed by RNA-polymerase II and DROSHA processed them into pre-miR-1–1 or pre-miR-1–2. The pre-miR-1 sequences then transported from the nucleus through exportin-5. Reaching out form the nucleus to cytoplasm, the pre-miR-1 sequences were processed by DICER and a single mature miR-1 was generated from both types of pre-sequences. The mature miR-1 was loaded to AGO2 that form miR-1-RISC complex for specific gene targeting or translation inhibition.