The M3/M4 cytoplasmic loop of the alpha1 subunit restricts GABAARs lateral mobility: a study using fluorescence recovery after photobleaching.
A crucial problem in neurobiology is how neurons are able to maintain neurotransmitter receptors at specific membrane domains. The large structural heterogeneity of gamma aminobutyric acid receptors (GABAARs) led to the hypothesis that there could be a link between GABAAR gene diversity and the targeting properties of the receptor complex. Previous studies using Fluorescence Recovery After Photobleaching (FRAP) have shown a restricted mobility in GABAARs containing the alpha1 subunit. The M3/M4 cytoplasmic loop is the region of the alpha1 subunit with the lowest sequence homology to other subunits. Therefore, we asked whether the M3/M4 loop is involved in cytoskeletal anchoring and GABAAR clustering. A series of alpha1 chimeric subunits was constructed: alpha1CH (control subunit), alpha1CD (Cytoplasmic loop deleted), alpha1CD2, and alpha1CD3 (alpha1 with the M3/M4 loop from the alpha2 and alpha3 subunits, respectively). Our results using FRAP indicate an involvement of the M3/M4 cytoplasmic loop of the alpha1 subunit in controlling receptor lateral mobility. On the other hand, inmunocytochemical approaches showed that this domain is not involved in subunit targeting to the cell surface, subunit-subunit assembly, or receptor aggregation.
Perán
Macarena
M
Department of Anatomy and Human Embryology, Faculty of Medicine, University of Granada, Granada, Spain. mperan@ugr.es
Hooper
Helen
H
Boulaiz
Houria
H
Marchal
Juan A
JA
Aránega
Antonia
A
Salas
Ramiro
R
D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000502:physiology* / Q000648:ultrastructure; D002465:Cell Movement; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism*; D005453:Fluorescence; D006801:Humans; D038761:Photobleaching; D021122:Protein Subunits; D021381:Protein Transport; D011940:Receptor Aggregation; D011963:Receptors, GABA-A / Q000502:physiology*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D021122:Protein Subunits; D011963:Receptors, GABA-A; D011994:Recombinant Proteins