APIM and PIP-box peptides have overlapping binding site on PCNA.

Abstract

<p>(A) Protein sequence and structural model of PCNA (PDB entry 1vym) with M40 highlighted in red and the center loop (CL) in yellow (upper panel). Live cell (HeLa) confocal fluorescence images of CFP-PCNA wild type (WT) and CFP-PCNA M40 mutants. Bar, 5 µm (lower panel). (B) Normalized FRET (N_FRET) measurements between WT and mutated CFP-PCNA M40/APIM-YFP (light grey diamonds, PCNA WT−/PCNA M40A−/PCNA M40N−/PCNA M40R−/PCNA M40S- APIM) and WT and mutated CFP-PCNA M40/PIP-YFP (dark grey diamonds, PCNA WT−/PCNA M40A−/PCNA M40N−/PCNA M40R/PCNA M40S- PIP). CFP/YFP (vectors only) was used as background control (open diamonds). Data is from three independent experiments (mean ± SEM, n = 72–214). P-values were calculated by the unpaired Student’s t-test.</p