Figure 6. Chemical (A) and enzymatic (B) methods for direct fluorophore labeling RNA.
(A) Direct labeling of RNA by chemical methods. Red circles are dye molecules. (B) Direct labeling of RNA by enzymatic methods. X represents appropriately modified NTPs that are either directly conjugated to fluorophores or contain functional groups for subsequent chemical conjugation of dyes. RNA pol, RNA polymerase; polyA pol, polyA polymerase; Capping Enz, 5‘ end capping enzyme; Klenow, Klenow fragment of DNA polymerase I from E. coli; Ligase, typically one of the two T4 RNA ligases.24