A four PDZ domain-containing splice variant form of GRIP1 is localized in GABAergic and glutamatergic synapses in the brain

Erik I. Charych, Wendou Yu, Rongwen Li, David R. Serwanski, Celia P. Miralles, Xuejing Li, Bih Y. Yang, Noelia Pinal, Randall Walikonis, Angel L. De Blas

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

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 α-amino-3-hydroxy-5-methyl-4- isoxazoleproprionic acid receptor. In low density hippocampal cultures, GRIP1c 4-7 clusters colocalized with GABAergic (where GABA is γ-aminobutyric acid) and glutamatergic synapses, although a higher percentage of GRIP1c 4-7 clusters colocalized with γ-aminobutyric acid, type A, receptor (GABA AR) clusters than with α-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 GABAAR 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.

Original languageEnglish (US)
Pages (from-to)38978-38990
Number of pages13
JournalJournal of Biological Chemistry
Volume279
Issue number37
DOIs
StatePublished - Sep 10 2004
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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