Fig. 1.

The framework of miRNA biogenesis and function. The transcription of pri-miRNAs is regulated by many transcription factors. Then, many protein factors are recruited to pri-miRNAs to form the processor complex of miRNAs through protein–protein and protein-RNA interactions. CDC5 and NOT2 do not interact with HYL1. Thus, whether CDC5 and NOT2 are in the D-body is unknown. After generation in nucleus, miRNA/miRNA* is methylated by HEN1 and exported into cytoplasm. miRNAs are loaded into AGO1 to direct target RNA cleavage or translational inhibition. It is not clear where the AGO1-miRNA assembly and miRNA methylation happens. Evidences suggest that translational inhibition by miRNA may occur at specific site of endoplasmic reticulum