Cloning and functional characterization of two glycine receptor alpha-subunits from the perch retina |
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Authors: | Gisselmann G Galler A Friedrich F Hatt H Bormann J |
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Institution: | Ruhr-University Bochum, Department of Cell Physiology, ND4, D-44780 Bochum, Germany. |
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Abstract: | Glycine receptors are ligand-gated ion channel proteins mediating synaptic inhibition in the spinal cord, retina and brain of vertebrates. We have cloned and functionally characterized two glycine receptor alpha-subunits from the perch (Roccus americana) retina. Based on sequence homology with the mammalian counterparts, we termed these subunits alpha 1 and alpha 3. RT-PCR revealed the presence of both subunits in retina and brain, whereas alpha1 was predominant in spinal cord. A short splice variant of alpha1 was detected in the brain but not in the retina. Functional expression of the perch subunits in HEK-293 cells yielded robust glycine-gated currents sensitive to strychnine. The perch receptors displayed a high efficacy for taurine and GABA and thus differ from the mammalian counterparts. Because the retina is a rich source for taurine, this finding could be of physiological importance. The structural features of the ligand binding domain strongly support the notion of increased glycine/GABA discrimination in higher vertebrates. |
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Keywords: | ion channel fish inhibition patch clamp cDNA |
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