RT Journal Article SR Electronic T1 Wheat Germ Agglutinin Conjugated Fluorescent pH Sensors for Visualizing Proton Fluxes JF bioRxiv FD Cold Spring Harbor Laboratory SP 781799 DO 10.1101/781799 A1 Lejie Zhang A1 Mei Zhang A1 Karl Bellve A1 Kevin Fogarty A1 Maite A. Castro A1 Sebastian Brauchi A1 William R. Kobertz YR 2019 UL http://biorxiv.org/content/early/2019/09/25/781799.abstract AB Small molecule fluorescent wheat germ agglutinin (WGA) conjugates are routinely used to demarcate mammalian plasma membranes because they bind to the cell’s glycocalyx. Here we describe the derivatization of WGA with a pH sensitive rhodamine fluorophore (pHRho: pKa = 7) to detect proton channel fluxes and extracellular proton accumulation and depletion from primary cells. We found that WGA-pHRho labeling was uniform, did not appreciably alter the voltage-gating of glycosylated ion channels, and the extracellular changes in pH directly correlated with proton channel activity. Using single plane illumination techniques, WGA-pHRho was used to detect spatiotemporal differences in proton accumulation and depletion over the extracellular surface of cardiomyocytes, astrocytes, and neurons. Because WGA can be derivatized with any small molecule fluorescent ion sensor, WGA conjugates should prove useful to visualize most electrogenic and non-electrogenic events on the extracellular side of the plasma membrane.