- See also RNA interference
Small interfering RNA (
siRNA), sometimes known as
short interfering RNA or
silencing RNA, is a class of
double-stranded RNA molecules, 20-25
base pairs in length. siRNA plays many roles, but it is most notable in the
RNA interference (RNAi) pathway, where it interferes with the
expression of specific genes with complementary nucleotide sequences. siRNA functions by causing mRNA to be broken down after transcription, resulting in no translation. siRNA also acts in RNAi-related pathways, e.g., as an antiviral mechanism or in shaping the
chromatin structure of a
genome. The complexity of these pathways is only now being elucidated.