Association of the AMPA receptor-related postsynaptic density proteins GRIP and ABP with subsets of glutamate-sensitive neurons in the rat retina.
We used specific antibodies against two postsynaptic density proteins, GRIP (glutamate receptor interacting protein) and ABP (AMPA receptor-binding protein), to study their distribution in the rat retina. In the central nervous system, it has been shown that both proteins bind strongly to the AMPA glutamate receptor (GluR) 2/3 subunits, but not other GluRs, through a set of three PDZ domains. Western blots detected a single GRIP protein that was virtually identical in retina and brain, whereas retinal ABP corresponded to only one of three ABP peptides found in brain. The retinal distributions of GluR2/3, GRIP, and ABP immunoreactivity (IR) were similar but not identical. GluR2/3 immunoreactivity (IR) was abundant in both plexiform layers and in large perikarya. ABP IR was concentrated in large perikarya but was sparse in the plexiform layers, whereas GRIP IR was relatively more abundant in the plexiform layers than in perikarya. Immunolabel for these three antibodies consisted of puncta < or = 0.2 microm in diameter. The cellular localization of GRIP and ABP IR was examined by double labeling subclasses of retinal neuron with characteristic marker proteins, e.g., calbindin. GRIP, ABP, and GluR2/3 IR were detected in horizontal cells, dopaminergic and glycinergic AII amacrine cells and large ganglion cells. Immunolabel was absent in rod bipolar and weak or absent in cholinergic amacrine cells. By using the tyramide method of signal amplification, a colocalization of GluR2/3 was found with either GRIP or ABP in horizontal cell terminals, and perikarya of amacrine and ganglion cells. Our results show that ABP and GRIP colocalize with GluR2/3 in particular subsets of retinal neuron, as was previously established for certain neurons in the brain.
Gábriel
Robert
R
Department of General Zoology and Neurobiology, University of Pécs, H-7604 Pécs, Hungary.
de Souza
Sunita
S
Ziff
Edward B
EB
Witkovsky
Paul
P
D000818:Animals; D002352:Carrier Proteins / Q000032:analysis / Q000378:metabolism*; D018698:Glutamic Acid / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000378:metabolism*; D009474:Neurons / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D020318:Rats, Long-Evans; D018091:Receptors, AMPA / Q000032:analysis / Q000378:metabolism; D012160:Retina / Q000737:chemistry / Q000378:metabolism*
D002352:Carrier Proteins; C491308:Grip1 protein, rat; C118486:Grip2 protein, rat; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D018091:Receptors, AMPA; C104723:glutamate receptor ionotropic, AMPA 3; C033652:postsynaptic density proteins; D018698:Glutamic Acid; C104722:glutamate receptor ionotropic, AMPA 2