FIG. 2.

Schematic of a canonical siRNA and several chemical and structural variations. The chemically modified small interfering RNA (siRNA) is not any specific siRNA reported in the literature, but rather a generic illustration of where some of the indicated chemical modifications can be placed. Red strands=passenger strands. Blue strands=guide strands. Dashed vertical grey line denotes the 5′ end of the guide strand of a canonical siRNA and the predicted 5′ end of the guide strand after Dicer processing for longer RNAi triggers. Figures not drawn to scale.