FIGURE 1.

5′-Adenylated RNA and its synthesis using protein enzymes. (A) Structure of 5′-adenylated RNA (5′-AppRNA). X denotes the nucleobase at the 5′-terminus of the RNA strand that is 5′-adenylated. (B) Synthesis of 5′-AppRNA using T4 RNA ligase and a complementary DNA oligonucleotide that leaves an RNA 5′-overhang (Silverman 2004). (C) Synthesis of 5′-AppRNA using T4 DNA ligase and a complementary DNA oligonucleotide that leaves a recessed RNA 5′-terminus (DNA 3′-overhang), as reported here.