Figure 1.

Proteasome-catalyzed peptide splicing and the investigated KRAS G12V cis-spliced and non-spliced peptides. (A) Proteasome-generated cis-spliced peptides can be formed by cis-PCPS, when the two splice-reactants, i.e. the non-contiguous peptide fragments ligated by proteasomes, derive from the same polypeptide molecule; the ligation can occur in normal order, i.e. following the orientation from N- to C-terminus of the parental protein (normal cis-PCPS), or in the reverse order (reverse cis-PCPS). (B) The KRAS_5-6/8-14 G12V [KL][VVGAVGV] cis-spliced peptide and the KRAS_5-13 G12V [KLVVVGAVG] non-spliced peptide, which are investigated in this study and derived from the KRAS_2-35 G12V synthetic substrate polypeptide. The G12V mutation is marked in bold.