A microRNA in a multiple-turnover RNAi enzyme complex

UMMS Affiliation

Department of Biochemistry and Molecular Pharmacology

Publication Date


Document Type



Adenosine Triphosphate; Animals; Base Pairing; Base Sequence; Cell Extracts; Cytoplasm; DEAD-box RNA Helicases; Drosophila melanogaster; Endoribonucleases; Eukaryotic Initiation Factor-2; *Eukaryotic Initiation Factors; *Gene Silencing; Hela Cells; Humans; MicroRNAs; Models, Genetic; Nuclear Proteins; Peptide Initiation Factors; Protein Biosynthesis; RNA Helicases; RNA, Antisense; RNA, Double-Stranded; RNA, Messenger; RNA, Small Interfering; RNA, Untranslated; RNA-Induced Silencing Complex; Ribonuclease III; Ribonucleoproteins; Ribonucleoproteins, Small Nuclear


Life Sciences | Medicine and Health Sciences


In animals, the double-stranded RNA-specific endonuclease Dicer produces two classes of functionally distinct, tiny RNAs: microRNAs (miRNAs) and small interfering RNAs (siRNAs). miRNAs regulate mRNA translation, whereas siRNAs direct RNA destruction via the RNA interference (RNAi) pathway. Here we show that, in human cell extracts, the miRNA let-7 naturally enters the RNAi pathway, which suggests that only the degree of complementarity between a miRNA and its RNA target determines its function. Human let-7 is a component of a previously identified, miRNA-containing ribonucleoprotein particle, which we show is an RNAi enzyme complex. Each let-7-containing complex directs multiple rounds of RNA cleavage, which explains the remarkable efficiency of the RNAi pathway in human cells.

DOI of Published Version



Science. 2002 Sep 20;297(5589):2056-60. Epub 2002 Aug 1. Link to article on publisher's site

Journal/Book/Conference Title

Science (New York, N.Y.)

Related Resources

Link to Article in PubMed

PubMed ID