Identification of a glutamate/aspartate transporter in the rat cochlea.
The neurotransmitter at the synapses between hair cells and spiral ganglion cells in the cochlea is probably L-glutamate or a similar excitatory amino acid. Glutamate uptake by nerve terminals and glial cells is an important component of neurotransmission at glutamatergic synapses of the central nervous system, for providing a reservoir of transmitter or transmitter precursors and the termination of the released glutamate. Hair cell synapses are not surrounded by glial cells, therefore, the uptake mechanism for glutamate in the cochlea may be unique. cDNA was synthesized from total RNA isolated separately from the rat organ of Corti, spiral ganglia, and lateral wall tissues. The expression of a glutamate/aspartate transporter (GLAST) was detected by DNA amplification with the polymerase chain reaction. The other two members of glutamate transporters in this family were not detected by this method. A partial cDNA encoding to GLAST was identified by sequence analysis in a rat cochlear cDNA library. Data concerning the expression and the molecular structure of the glutamate transporter GLAST in the cochlea may provide important information regarding the neurotransmission process at the hair cell-afferent synapses.
Li
H S
HS
Boys Town National Research Hospital, Omaha, NE 68131.
Niedzielski
A S
AS
Beisel
K W
KW
Hiel
H
H
Wenthold
R J
RJ
Morley
B J
BJ
D000595:Amino Acid Sequence; D027322:Amino Acid Transport System X-AG; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D003051:Cochlea / Q000378:metabolism*; D017931:DNA Primers / Q000737:chemistry; D018076:DNA, Complementary / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D004587:Electrophoresis, Agar Gel; D005786:Gene Expression Regulation / Q000235:genetics*; D015723:Gene Library; D018698:Glutamic Acid / Q000378:metabolism*; D006023:Glycoproteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D006198:Hair Cells, Auditory / Q000378:metabolism; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009457:Neuroglia / Q000502:physiology; D016366:Open Reading Frames; D009925:Organ of Corti / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013136:Spiral Ganglion / Q000378:metabolism; D009435:Synaptic Transmission / Q000235:genetics* / Q000502:physiology
D027322:Amino Acid Transport System X-AG; D002352:Carrier Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D006023:Glycoproteins; D018698:Glutamic Acid; D012313:RNA