PEPCy: Photostable fluoromodules for live cell, super-resolution microscopy of surface proteins

Abstract

We report the evolution and application of two genetically encoded tags that bind the cyanine dyes Cy3 or Cy5 with high specificity and selectivity, in addition to enhancing their photostability. These tags, which we call PEPCy, can be used to target membrane proteins such as G-protein coupled receptors. Due to their orthogonality and high binding-affinity for cognate cyanine dyes, the PEPCy tags can be used for wash-free labeling of cell surface receptors to observe their dynamics at a single molecule level. Together with self-labeling tags, these photostability enhancing proteins against cyanine dyes present a novel, complementary and powerful approach to explore protein dynamics with high spatiotemporal resolution.