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

Xingjuan Chen, Wennan Li, Ashley M. Riley, Mario Soliman, Saikat Chakraborty, Christopher W. Stamatkin, Alexander Obukhov

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10 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)898-911
Number of pages14
JournalJournal of Biological Chemistry
Issue number3
StatePublished - Jan 20 2017

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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