Szerkesztő:Alfa-ketosav/piRNS
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A Piwi-kölcsönható RNS (piRNS) kis nemkódoló RNS-ek állati sejtekben expresszált legnagyobb csoportja.[1][2][3] RNS-fehérje komplexeket alkotnak a piwi-alcsaládba tartozó Argonaute fehérjékkel.[4][5][6]
piRNAs are mostly created from loci that function as transposon traps which provide a kind of RNA-mediated adaptive immunity against transposon expansions and invasions.[7] They are distinct from microRNA (miRNA) in size (26–31 nucleotides as opposed to 21–24 nt), lack of sequence conservation, increased complexity, and independence of Dicer for biogenesis, at least in animals.[5][1][2] (Plant Dcl2 may play a role in rasi/piRNA biogenesis.)[8][9]
Double-stranded RNAs capable of silencing repeat elements, then known as repeat associated small interfering RNA (rasiRNA), were proposed in Drosophila in 2001.[10] By 2008, it was still unclear how piRNAs are generated, but potential methods had been suggested, and it was certain their biogenesis pathway is distinct from miRNA and siRNA, while rasiRNA is now considered a piRNA subspecies.[11]