Quantitative Subcellular Analysis of Cyclic Cell-Penetrating Peptide EJP18 in Nonadherent Cells

Cyclization of cell-penetrating peptides (CPPs) often results in improved capacity for intracellular delivery of a range of cargoes but quantitating the distinct subcellular localization of them, and their linear counterparts, remains a challenge. Here we describe an optimized method for recombinant generation and purification of eGFP attached to the cyclic form of the newly discovered CPP EJP18 in E. coli. We also demonstrate a novel microscopy method for quantifying its subcellular distribution in leukemia cells.