Is mRNA spliced with very small fragment treated with siRNA? - (Nov/23/2004 )
Is mRNA spliced with very small fragment treated with siRNA or splice only the targeted sequence,Don't breakage other sequence?
hm, don't quite understand what you are saying. mRNA splicing and siRNA are two different things.
I guess you want to know whether the RISC will cut the target mRNA into two fragments or it would chew up mRNA into many pieces. I was wondering this and had a chat with Invitrogen tech. They said that the RISC would cut once about 10bp down stream of the target mRNA from where siRNA was binding; therefore you would have two piecies of cleaved traget mRNA after the RISC woking on it.
According to the litterature, siRNA recognize a sequence of target mRNA (triple helix structure? remains unclear). The risc complex gets an endonuclease activity, then as akim said cuts tha target about 10 bp downstream of the recognition sequence. Then the two parts of cleaved mRNA are degraded by the cell machinery. And it's admitted that there is no transcription of the mRNA fragment.