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shRNA/siRNA stem length 19, 20, or 21? - (Aug/07/2006 )

Dear all,

Has anybody tested or read about the difference in effectiveness of small hairpin / small interfering RNAs with stems of 19, 20, or 21 nts? The only thing I have found so far is different statements without explanations: Tuschl 21nt, Promega shRNA designer 19,...

Hope you guys know. Many thanks, ~j


For some 19mers seemed fine and others 21mers seem fine. But I would stick with 21mers.


Hey! I suggest you to read this pdf where they explain the structure and the importance of the stem in RNAi pathway!


Thanks nonsensey for suggesting this paper. I found a lot of interesting info on the lack of importance of the loop smile.gif (see my other topic 18878) but during a brief scan of the paper, I couldn't find recommendations on the length of the stem. I am still wondering whether it should be 19, 20, or 21 nts. dry.gif

Ciao, j