Functional integrity of green fluorescent protein conjugated glycine receptor channels

The alpha subunit (alpha Z1) of the zebrafish glycine receptor (GlyR) has been N-terminus fused with green fluorescent protein (GFP). We found that both pharmacological and electrophysiological properties of this chimeric alpha Z1-GFP are indistinguishable from those of the wild-type receptor when expressed in Xenopus oocytes and cell lines. The apparent affinities of this receptor for agonists (glycine, taurine and GABA), and the antagonist (strychnine) are unchanged, and single channel kinetics are not altered. In the same expression systems, alpha Z1-GFP was visualized using fluorescence microscopy. Fluorescence was distributed anisotropically across cellular membranes. In addition to the Golgi apparatus and endoplasmic reticulum, its presence was also detected on the plasmalemma, localized at discrete hot-spots which were identified as sites of high membrane turnover. Overall, the preservation in alpha Z1-GFPs of the wild type receptor functional properties makes it a promising new tool for further in situ investigations of GlyR expression, distribution and function. (C) 1999 Elsevier Science Ltd. All rights reserved.