Cloning and functional characterization of two glycine receptor alpha-subunits from the perch retina.
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.
Gisselmann
G
G
Ruhr-University Bochum, Department of Cell Physiology, ND4, D-44780 Bochum, Germany.
Galler
A
A
Friedrich
F
F
Hatt
H
H
Bormann
J
J
D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry; D003001:Cloning, Molecular; D004594:Electrophysiology; D018756:GABA Antagonists / Q000494:pharmacology; D005998:Glycine / Q000493:pharmacokinetics; D018684:Glycine Agents / Q000494:pharmacology; D008969:Molecular Sequence Data; D010471:Perches; D010852:Picrotoxin / Q000494:pharmacology; D018009:Receptors, Glycine / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D012160:Retina / Q000737:chemistry*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013116:Spinal Cord / Q000737:chemistry; D013331:Strychnine / Q000494:pharmacology; D013654:Taurine / Q000493:pharmacokinetics; D005680:gamma-Aminobutyric Acid / Q000493:pharmacokinetics
D018756:GABA Antagonists; D005998:Glycine; D018684:Glycine Agents; D010852:Picrotoxin; D018009:Receptors, Glycine; D013331:Strychnine; D013654:Taurine; D005680:gamma-Aminobutyric Acid; C113965:glycine receptor alpha3 subunit