How siRNA silences gene expression
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Long dsRNA which can come from the following sources: hairpin, complementary RNAs, RNA dependent RNA polymerases. The long dsRNA is cleaved by an endo-ribonuclease called Dicer. Dicer cuts the long dsRNA to form short interfering RNA or siRNA.Once siRNA enters the cell it gets incorporated into other proteins to form the RNA-induced Silencing Complex or RISC.Once the siRNA is part of the RISC complex, the siRNA is unwound to form single stranded siRNA.One of the single stranded siRNAs is chosen at random to stay as part of the RISC complex.The single stranded siRNA which is part of the RISC complex now can scan and find a complementary mRNAOnce the single stranded siRNA (part of the RISC complex) binds to its target mRNA, it induces mRNA cleavage.The mRNA is now cut and recognized as abnormal by the cell. This causes degradation of the mRNA and in turn no translation of the mRNA into amino acids and then proteins. Thus silencing the gene that encodes that mRNA.
siRNA is also similar to miRNA, however, miRNA silences genes by repression of translation, while siRNA works by cleaving the mRNA before translation.
Long dsRNA which can come from the following sources: hairpin, complementary RNAs, RNA dependent RNA polymerases. The long dsRNA is cleaved by an endo-ribonuclease called Dicer. Dicer cuts the long dsRNA to form short interfering RNA or siRNA.Once siRNA enters the cell it gets incorporated into other proteins to form the RNA-induced Silencing Complex or RISC.Once the siRNA is part of the RISC complex, the siRNA is unwound to form single stranded siRNA.One of the single stranded siRNAs is chosen at random to stay as part of the RISC complex.The single stranded siRNA which is part of the RISC complex now can scan and find a complementary mRNAOnce the single stranded siRNA (part of the RISC complex) binds to its target mRNA, it induces mRNA cleavage.The mRNA is now cut and recognized as abnormal by the cell. This causes degradation of the mRNA and in turn no translation of the mRNA into amino acids and then proteins. Thus silencing the gene that encodes that mRNA.
siRNA is also similar to miRNA, however, miRNA silences genes by repression of translation, while siRNA works by cleaving the mRNA before translation.
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