Molecular Determinants of the Sensitivity to Gq/11-Phospholipase C-dependent Gating, Gd3+ Potentiation, and Ca2+ Permeability in the Transient Receptor Potential Canonical Type 5 (TRPC5) Channel.
J Biol Chem
; 292(3): 898-911, 2017 01 20.
Article
en En
| MEDLINE
| ID: mdl-27920205
ABSTRACT
Transient receptor potential canonical type 5 (TRPC5) is a Ca2+-permeable cation channel that is highly expressed in the brain and is implicated in motor coordination, innate fear behavior, and seizure genesis. The channel is activated by a signal downstream of the G-protein-coupled receptor (GPCR)-Gq/11-phospholipase C (PLC) pathway. In this study we aimed to identify the molecular mechanisms involved in regulating TRPC5 activity. We report that Arg-593, a residue located in the E4 loop near the TRPC5 extracellular Gd3+ binding site, is critical for conferring the sensitivity to GPCR-Gq/11-PLC-dependent gating on TRPC5. Indeed, guanosine 5'-O-(thiotriphosphate) and GPCR agonists only weakly activate the TRPC5R593A mutant, whereas the addition of Gd3+ rescues the mutant's sensitivity to GPCR-Gq/11-PLC-dependent gating. Computer modeling suggests that Arg-593 may cross-bridge the E3 and E4 loops, forming the "molecular fulcrum." While validating the model using site-directed mutagenesis, we found that the Tyr-542 residue is critical for establishing a functional Gd3+ binding site, the Tyr-541 residue participates in fine-tuning Gd3+-sensitivity, and that the Asn-584 residue determines Ca2+ permeability of the TRPC5 channel. This is the first report providing molecular insights into the molecular mechanisms regulating the sensitivity to GPCR-Gq/11-PLC-dependent gating of a receptor-operated channel.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Fosfolipasas de Tipo C
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Activación del Canal Iónico
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Señalización del Calcio
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Subunidades alfa de la Proteína de Unión al GTP Gq-G11
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Canales Catiónicos TRPC
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Gadolinio
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Modelos Biológicos
Tipo de estudio:
Diagnostic_studies
Límite:
Animals
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Humans
Idioma:
En
Revista:
J Biol Chem
Año:
2017
Tipo del documento:
Article
Pais de publicación:
EEUU
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ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
/
EUA
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UNITED STATES
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UNITED STATES OF AMERICA
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US
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USA