Functional integrity of green fluorescent protein conjugated glycine receptor channels

The alpha subunit (alpha Z1) of the zebrafish glycine receptor (GlyR) has b een N-terminus fused with green fluorescent protein (GFP). We found that bo th pharmacological and electrophysiological properties of this chimeric alp ha Z1-GFP are indistinguishable from those of the wild-type receptor when e xpressed in Xenopus oocytes and cell lines. The apparent affinities of this receptor for agonists (glycine, taurine and GABA), and the antagonist (str ychnine) are unchanged, and single channel kinetics are not altered. In the same expression systems, alpha Z1-GFP was visualized using fluorescence mi croscopy. Fluorescence was distributed anisotropically across cellular memb ranes. In addition to the Golgi apparatus and endoplasmic reticulum, its pr esence was also detected on the plasmalemma, localized at discrete hot-spot s which were identified as sites of high membrane turnover. Overall, the pr eservation in alpha Z1-GFPs of the wild type receptor functional properties makes it a promising new tool for further in situ investigations of GlyR e xpression, distribution and function. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.