Fig. 1: Diversity of proline codons and their corresponding tRNAs.

a The genetic code contains four codons for proline: CCG, CCC, CCU, and CCA. b The three tRNAs ProK, ProL, and ProM recognize distinct sets of proline codons and exhibit different levels of abundance within the cell34. All three prolyl-tRNAs are charged by the prolyl-tRNA synthetase ProS.