Ggamma13 interacts with PDZ domain-containing proteins.
The G protein gamma13 subunit (Ggamma13) is expressed in taste and retinal and neuronal tissues and plays a key role in taste transduction. We identified PSD95, Veli-2, and other PDZ domain-containing proteins as binding partners for Ggamma13 by yeast two-hybrid and pull-down assays. In two-hybrid assays, Ggamma13 interacted specifically with the third PDZ domain of PSD95, the sole PDZ domain of Veli-2, and the third PDZ domain of SAP97, a PSD95-related protein. Ggamma13 did not interact with the other PDZ domains of PSD95. Coexpression of Ggamma13 with its Gbeta1 partner did not interfere with these two-hybrid interactions. The physical interaction of Ggamma13 with PSD95 in the cellular milieu was confirmed in pull-down assays following heterologous expression in HEK293 cells. The interaction of Ggamma13 with the PDZ domain of PSD95 was via the C-terminal CAAX tail of Ggamma13 (where AA indicates the aliphatic amino acid); alanine substitution of the CTAL sequence at the C terminus of Ggamma13 abolished its interactions with PSD95 in two-hybrid and pull-down assays. Veli-2 and SAP97 were identified in taste tissue and in Ggamma13-expressing taste cells. Coimmunoprecipitation of Ggamma13 and PSD95 from brain and of Ggamma13 and SAP97 from taste tissue indicates that Ggamma13 interacts with these proteins endogenously. This is the first demonstration that PDZ domain proteins interact with heterotrimeric G proteins via the CAAX tail of Ggamma subunits. The interaction of Ggamma13 with PDZ domain-containing proteins may provide a means to target particular Gbetagamma subunits to specific subcellular locations and/or macromolecular complexes involved in signaling pathways.
Li
Zairong
Z
Department of Neuroscience, Mount Sinai School of Medicine, New York, New York 10029, USA.
Benard
Outhiriaradjou
O
Margolskee
Robert F
RF
D000409:Alanine / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000196:embryology / Q000378:metabolism; D002460:Cell Line; D018076:DNA, Complementary / Q000378:metabolism; D000076122:Disks Large Homolog 4 Protein; D004591:Electrophoresis, Polyacrylamide Gel; D019204:GTP-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D051528:Guanylate Kinases; D020962:Heterotrimeric GTP-Binding Proteins / Q000737:chemistry* / Q000502:physiology*; D006801:Humans; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry; D010802:Phylogeny; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013649:Taste; D020798:Two-Hybrid System Techniques
C501444:DLG4 protein, human; D018076:DNA, Complementary; D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; C510865:Ggamma13 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; C114671:LIN7B protein, human; C485432:Lin7b protein, mouse; D008055:Lipids; D008565:Membrane Proteins; D009841:Oligonucleotides; D051528:Guanylate Kinases; D019204:GTP-Binding Proteins; D020962:Heterotrimeric GTP-Binding Proteins; D000409:Alanine