Tax1-binding protein 1 is expressed in the retina and interacts with the GABA(C) receptor rho1 subunit.
Macromolecular signalling complexes that link neurotransmitter receptors to functionally and structurally associated proteins play an important role in the regulation of neurotransmission. Thus the identification of proteins binding to neurotransmitter receptors describes molecular mechanisms of synaptic signal transduction. To identify interacting proteins of GABA(C) (where GABA is gamma-aminobutyric acid) receptors in the retina, we used antibodies specific for GABA(C) receptor rho1-3 subunits. Analysis of immunoprecipitated proteins by MALDI-TOF MS (matrix-assisted laser-desorption ionization-time-of-flight MS) identified the liver regeneration-related protein 2 that is identical with amino acids 253-813 of the Tax1BP1 (Tax1-binding protein 1). A C-terminal region of Tax1BP1 bound to an intracellular domain of the rho1 subunit, but not to other subunits of GABA(C), GABA(A) or glycine receptors. Confocal laser-scanning microscopy demonstrated co-localization of Tax1BP1 and rho1 in clusters at the cell membrane of transfected cells. Furthermore, Tax1BP1 and GABA(C) receptors were co-expressed in both synaptic layers of the retina, indicating that Tax1BP1 is a component of GABA(C) receptor-containing signal complexes.
Ulrich
Melanie
M
Emil-Fischer-Zentrum, Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Fahrstr. 17, 91054 Erlangen, Germany.
Seeber
Silke
S
Becker
Cord-Michael
CM
Enz
Ralf
R
D000818:Animals; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000378:metabolism; D002478:Cells, Cultured; D006801:Humans; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D051381:Rats; D018079:Receptors, GABA / Q000276:immunology / Q000378:metabolism*; D011963:Receptors, GABA-A; D012160:Retina / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D020798:Two-Hybrid System Techniques
D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; C528239:Gabrr1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D018079:Receptors, GABA; D011963:Receptors, GABA-A; C516163:Tax1-binding protein 1, rat