Figure 1.

Comparison of ssRNA and dsRNA oligos containing pyrimidine (Y) and purine (R) 2' modifications. ApoB (8786) sequence shown. In vitro cell-based evaluation of ApoB mRNA knockdown (error bars represent standard deviation of four replicates). Unmodified ribose (‘r’) is compared to 2'-fluoro (‘f’), 2'-methoxy (‘m’), and 2'-deoxy (‘d’) in all combinations on purines (R) and pyrimidines (Y). Oligos do not contain a 5' phosphate. Guide strand oligo sequence and color-coded modification patterns are depicted. Five other siRNAs were tested and a similar requirement of 2'F for ssRNA knockdown was observed (Supplementary Figure S1).