Cell surface immobilization of GABAA Rs in cerebellar granule cells depends on the M3/M4 cytoplasmatic loop of the alpha 1 subunit.
Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the vertebrate brain. The localization of GABA receptors type A (GABA(A)Rs) at strategically located domains of the neuronal membrane is of vital importance for fast inhibitory synapse transmission efficacy. We have shown before that the lateral mobility of GABA(A)Rs depends on subunit composition of the complex. To study the lateral mobility of GABA(A)Rs in living, cultured neurons, we transfected cerebellar granule cells with either the complete alpha1 GABA(A)R subunit or with a truncation of the alpha1 subunit that lacks the major intracellular loop (M3/M4). We examined the location and lateral mobility of receptors containing both versions of the alpha1 subunit in living neurons. From fluorescence recovery after photobleaching experiments we present novel evidences that the intracellular M3/M4 loop of the alpha1 subunit restricts the lateral mobility of GABA(A)Rs when expressed in neurons. In addition, our immunocytochemical studies suggested that receptors containing the truncated subunit seem to be unable to reach synaptic localizations. Here we show for the first time that the alpha1 intracellular loop (M3/M4) domain has a relevant role in controlling the lateral mobility of GABA(A)Rs in neurons, and we believe that this is a novel and important contribution in neurobiology of GABA(A) receptors.
Perán
Macarena
M
Department of Health Sciences, University of Jaén, Jaén, Spain. mperan@ujaen.es
Hooper
Helen
H
Marchal
Juan A
JA
Boulaiz
Houria
H
Rodríguez-Serrano
Fernando
F
Velez
Celia
C
Aránega
Antonia
A
Salas
Ramiro
R
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure; D002465:Cell Movement; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology* / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism*; D005453:Fluorescence; D006801:Humans; D051379:Mice; D011963:Receptors, GABA-A / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid