Brain distribution and molecular cloning of the bovine GABA rho1 receptor.
GABA(C) receptors were originally found in the mammalian retina and recent evidence shows that they are also expressed in several areas of the brain, including caudate nucleus, brain stem, pons and corpus callosum. In this study, plasma membranes from the caudate nucleus were microinjected into X. laevis oocytes. This led the oocyte plasma membrane to incorporate functional bicuculline-resistant, Cl(-) conducting bovine GABA receptors, similar to those of the retina. Immunolocalization of the GABA rho1 subunit revealed its expression in bovine neurons in the head of the caudate as well as in the olive, cuneiform and reticular nuclei of the brain stem. The same antibodies failed to show expression in the callosum and pons, where the GABA rho1 mRNA was previously detected. The cloned GABA rho1 sequence predicts a protein with 473 amino acids and 74-93% similarity to other GABA rho1 subunits. Oocytes injected with the cDNA express a non-desensitizing, homomeric receptor with a GABA EC(50)=6.0 microM and a Hill coefficient of 1.8. The results confirm the presence of GABA(C) receptor mRNAs in several areas of the mammalian brain and show that some of these areas express functional GABA rho1 receptors that have the classic GABA(C) receptor characteristics.
Rosas-Arellano
Abraham
A
Instituto de Neurobiología, Laboratorio de Neurobiología Molecular y Celular II, Universidad Nacional Autónoma de México, Km 15.5 Carretera a San Luis Potosí 76001 Juriquilla, Querétaro, México.
Ochoa-de la Paz
Lenin David
LD
Miledi
Ricardo
R
Martínez-Torres
Ataúlfo
A
D000595:Amino Acid Sequence; D000818:Animals; D001001:Anura; D001483:Base Sequence; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D002417:Cattle; D002421:Caudate Nucleus / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D018118:Chloride Channels / Q000378:metabolism; D003001:Cloning, Molecular; D005260:Female; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D009865:Oocytes; D018079:Receptors, GABA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018080:Receptors, GABA-B / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D009435:Synaptic Transmission / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D018118:Chloride Channels; C087200:GABA-C receptor; D018079:Receptors, GABA; D018080:Receptors, GABA-B; D005680:gamma-Aminobutyric Acid