FIGURE 1.

Schematic of coding end processing leading to P-nucleotide and Pr-nucleotide inserts at coding joints. A, The formation of a coding joint with P-nucleotides and N-nucleotide additions. B, The exonucleolytic processing at the 5′ coding end and the generation of Pr-nucleotides. Filled and open triangles represent the RSS sites. Bolded nucleotides are from the coding end. Uppercase unbolded nucleotides are P-nucleotides. Ns represent N-nucleotides whereas lowercase nucleotides are Pr-nucleotides (N-nucleotides that result in an inverted repeat).