A four PDZ domain-containing splice variant form of GRIP1 is localized in GABAergic and glutamatergic synapses in the brain.
We have isolated, from a rat brain cDNA library, a clone corresponding to a 2779-bp cDNA encoding a novel splice form of the glutamate receptor interacting protein-1 (GRIP1). We call this 696-amino acid splice form GRIP1c 4-7 to differentiate it from longer splice forms of GRIP1a/b containing seven PDZ domains. The four PDZ domains of GRIP1c 4-7 are identical to PDZ domains 4-7 of GRIP1a/b. GRIP1c 4-7 also contains 35 amino acids at the N terminus and 12 amino acids at the C terminus that are different from GRIP1a/b. In transfected HEK293 cells, a majority of GRIP1c 4-7 was associated with the plasma membrane. GRIP1c 4-7 interacted with GluR2/3 subunits of the alpha-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid receptor. In low density hippocampal cultures, GRIP1c 4-7 clusters colocalized with GABAergic (where GABA is gamma-aminobutyric acid) and glutamatergic synapses, although a higher percentage of GRIP1c 4-7 clusters colocalized with gamma-aminobutyric acid, type A, receptor (GABA(A)R) clusters than with alpha-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid receptor clusters. Transfection of hippocampal neurons with hemagglutinin-tagged GRIP1c 4-7 showed that it could target to the postsynaptic complex of GABAergic synapses colocalizing with GABA(A)R clusters. GRIP1c 4-7-specific antibodies, which did not recognize previously described splice forms of GRIP1, recognized a 75-kDa protein that is enriched in a postsynaptic density fraction isolated from rat brain. EM immunocytochemistry experiments showed that in intact brain GRIP1c 4-7 concentrates at postsynaptic complexes of both type I glutamatergic and type II GABAergic synapses although it is also presynaptically localized. These results indicate that GRIP1c 4-7 plays a role not only in glutamatergic synapses but also in GABAergic synapses.
Charych
Erik I
EI
Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269, USA.
Yu
Wendou
W
Li
Rongwen
R
Serwanski
David R
DR
Miralles
Celia P
CP
Li
Xuejing
X
Yang
Bih Y
BY
Pinal
Noelia
N
Walikonis
Randall
R
De Blas
Angel L
AL
D020121:5' Untranslated Regions; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis / Q000737:chemistry*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D018683:Excitatory Amino Acid Agents / Q000378:metabolism*; D018682:GABA Agents / Q000378:metabolism*; D015723:Gene Library; D006056:Golgi Apparatus / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000737:chemistry*; D009474:Neurons / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000096:biosynthesis / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D013569:Synapses / Q000378:metabolism*; D014162:Transfection; D020798:Two-Hybrid System Techniques
D020121:5' Untranslated Regions; D002352:Carrier Proteins; D018076:DNA, Complementary; D018683:Excitatory Amino Acid Agents; D018682:GABA Agents; C491310:GRIP1 protein, human; C491308:Grip1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D018091:Receptors, AMPA