title: GABAA receptor-associated protein traffics GABAA receptors to the plasma membrane in neurons.
abstract: The trafficking of GABA(A) receptors is an important component of the pathway that regulates plasticity of inhibitory synapses. The 17 kDa GABA(A) receptor-associated protein (GABARAP) has been implicated in the trafficking of GABA(A) receptors because of its ability to interact not only with the gamma2 subunit of the receptor but also with microtubules and the N-ethylmaleimide-sensitive factor (NSF). To elucidate the role of GABARAP in the trafficking of GABA(A) receptors, we have constructed a yellow fluorescent protein (YFP) fusion protein of GABARAP and expressed it in neurons using adenovirus, so that its function may be examined. YFP-GABARAP colocalized with gamma2 subunit-containing GABA(A) receptors and NSF to the perinuclear cytoplasm in cultured hippocampal neurons and to the proximal regions of dendrites that are making synaptic contact. Expression of YFP-GABARAP in Cos7 cells and cultured hippocampal neurons was able to increase the level of GABA(A) receptors detected at the plasma membrane, even at low levels of YFP-GABARAP expression. This effect is specific to the function of GABARAP on GABA(A) receptor trafficking, because point mutations in the gamma2-binding domain of YFP-GABARAP interfered with the ability of YFP-GABARAP to increase GABA(A) receptor surface levels. These mutations also disrupted the colocalization of YFP-GABARAP with the gamma2 subunit and with NSF in hippocampal neurons. The results of this study show for the first time that GABARAP has a functional effect on the trafficking of GABA(A) receptors and provide decisive evidence for the role of GABARAP in transporting GABA(A) receptors to the plasma membrane in neurons.
authors.affiliation: Department of Molecular and Medical Pharmacology, Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095-1735.
authors.forename: Tarek A
authors.initials: TA
authors.lastname: Leil
authors.forename: Zi-Wei
authors.initials: ZW
authors.lastname: Chen
authors.forename: Chang-Sheng S
authors.initials: CS
authors.lastname: Chang
authors.forename: Richard W
authors.initials: RW
authors.lastname: Olsen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D006624:Hippocampus / Q000196:embryology / Q000378:metabolism; D008164:Luminescent Proteins; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000502:physiology*; D008969:Molecular Sequence Data; D052066:N-Ethylmaleimide-Sensitive Proteins; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000502:physiology*; D009474:Neurons / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D011963:Receptors, GABA-A / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: C502186:GABARAP protein, rat; D008164:Luminescent Proteins; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D011963:Receptors, GABA-A; D011993:Recombinant Fusion Proteins; D033921:Vesicular Transport Proteins; D052066:N-Ethylmaleimide-Sensitive Proteins; C498737:Nsf protein, rat