Tamalin, a PDZ domain-containing protein, links a protein complex formation of group 1 metabotropic glutamate receptors and the guanine nucleotide exchange factor cytohesins.
In this investigation, we report identification and characterization of a 95 kDa postsynaptic density protein (PSD-95)/discs-large/ZO-1 (PDZ) domain-containing protein termed tamalin, also recently named GRP1-associated scaffold protein (GRASP), that interacts with group 1 metabotropic glutamate receptors (mGluRs). The yeast two-hybrid system and in vitro pull-down assays indicated that the PDZ ... domain-containing, amino-terminal half of tamalin directly binds to the class I PDZ-binding motif of group 1 mGluRs. The C-terminal half of tamalin also bound to cytohesins, the members of guanine nucleotide exchange factors (GEFs) specific for the ADP-ribosylation factor (ARF) family of small GTP-binding proteins. Tamalin mRNA is expressed predominantly in the telencephalic region and highly overlaps with the expression of group 1 mGluR mRNAs. Both tamalin and cytohesin-2 were enriched and codistributed with mGluR1a in postsynaptic membrane fractions. Importantly, recombinant and native mGluR1a/tamalin/cytohesin-2 complexes were coimmunoprecipitated from transfected COS-7 cells and rat brain tissue, respectively. Transfection of tamalin and mutant tamalin lacking a cytohesin-binding domain caused an increase and decrease in cell-surface expression of mGluR1a in COS-7 cells, respectively. Furthermore, adenovirus-mediated expression of tamalin and dominant-negative tamalin facilitated and reduced the neuritic distribution of endogenous mGluR5 in cultured hippocampal neurons, respectively. The results indicate that tamalin plays a key role in the association of group 1 mGluRs with the ARF-specific GEF proteins and contributes to intracellular trafficking and the macromolecular organization of group 1 mGluRs at synapses.
Mesh Terms:
ADP-Ribosylation Factors, Animals, Brain Chemistry, COS Cells, Carrier Proteins, Cell Adhesion Molecules, Cells, Cultured, Cloning, Molecular, Guanine Nucleotide Exchange Factors, Humans, In Situ Hybridization, Macromolecular Substances, Membrane Proteins, Mice, Molecular Sequence Data, Neurons, Organ Specificity, Precipitin Tests, Protein Structure, Tertiary, Protein Transport, RNA, Messenger, Rats, Receptors, Metabotropic Glutamate, Sequence Homology, Amino Acid, Transfection, Two-Hybrid System Techniques
ADP-Ribosylation Factors, Animals, Brain Chemistry, COS Cells, Carrier Proteins, Cell Adhesion Molecules, Cells, Cultured, Cloning, Molecular, Guanine Nucleotide Exchange Factors, Humans, In Situ Hybridization, Macromolecular Substances, Membrane Proteins, Mice, Molecular Sequence Data, Neurons, Organ Specificity, Precipitin Tests, Protein Structure, Tertiary, Protein Transport, RNA, Messenger, Rats, Receptors, Metabotropic Glutamate, Sequence Homology, Amino Acid, Transfection, Two-Hybrid System Techniques
J. Neurosci.
Date: Feb. 15, 2002
PubMed ID: 11850456
View in: Pubmed Google Scholar
Download Curated Data For This Publication
56768
Switch View:
- Interactions 11