Enzymes RdRP

Fig. 2 The RNAi mechanisms. In the cytoplasm, dsRNA is cleaved into 22nt fragments called small interfering RNAs (siRNAs) by the RNase III t5rpe enzyme Dicer. The siRNAs are unwound and serve either as primers for RdRP (left) in some taxa (e.g., plants and nematodes) or, more universally, as guide strand in the RISC (right). RdRP creates additional dsRNA, amplifying the substrate for Dicer. RISC cleaves the target RNA in the region bound by the siRNA guide.

Fig. 1. Model for HCV RNA replication. The diagram shows the putative formation and function of the HCV replication complex that involves the RNA-dependent RNA polymerase (RdRp) together with the NS3/4A multifunctional enzyme. The RdRp catalyzes the formation of phosphodiester bonds between adjacent nucleotides, and the helicase separates the two RNA strands after synthesis.

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