title: Conserved gating elements in TRPC4 and TRPC5 channels.
abstract: TRPC4 and TRPC5 proteins share 65% amino acid sequence identity and form Ca(2+)-permeable nonselective cation channels. They are activated by stimulation of receptors coupled to the phosphoinositide signaling cascade. Replacing a conserved glycine residue within the cytosolic S4-S5 linker of both proteins by a serine residue forces the channels into an open conformation. Expression of the TRPC4G503S and TRPC5G504S mutants causes cell death, which could be prevented by buffering the Ca(2+) of the culture medium. Current-voltage relationships of the TRPC4G503S and TRPC5G504S mutant ion channels resemble that of fully activated TRPC4 and TRPC5 wild-type channels, respectively. Modeling the structure of the transmembrane domains and the pore region (S4-S6) of TRPC4 predicts a conserved serine residue within the C-terminal sequence of the predicted S6 helix as a potential interaction site. Introduction of a second mutation (S623A) into TRPC4G503S suppressed the constitutive activation and partially rescued its function. These results indicate that the S4-S5 linker is a critical constituent of TRPC4/C5 channel gating and that disturbance of its sequence allows channel opening independent of any sensor domain.
authors.affiliation: Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany. andreas.beck@uniklinikum-saarland.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Beck
authors.forename: Tilman
authors.initials: T
authors.lastname: Speicher
authors.forename: Christof
authors.initials: C
authors.lastname: Stoerger
authors.forename: Thomas
authors.initials: T
authors.lastname: Sell
authors.forename: Viviane
authors.initials: V
authors.lastname: Dettmer
authors.forename: Siti A
authors.initials: SA
authors.lastname: Jusoh
authors.forename: Ammar
authors.initials: A
authors.lastname: Abdulmughni
authors.forename: Adolfo
authors.initials: A
authors.lastname: Cavalié
authors.forename: Stephan E
authors.initials: SE
authors.lastname: Philipp
authors.forename: Michael X
authors.initials: MX
authors.lastname: Zhu
authors.forename: Volkhard
authors.initials: V
authors.lastname: Helms
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wissenbach
authors.forename: Veit
authors.initials: V
authors.lastname: Flockerzi
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D057809:HEK293 Cells; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology*; D051379:Mice; D008958:Models, Molecular; D020125:Mutation, Missense; D010449:Peptide Mapping; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D051381:Rats; D050052:TRPC Cation Channels / Q000235:genetics / Q000378:metabolism*
chemical_list: D050052:TRPC Cation Channels; C489571:TRPC4 ion channel; C491780:TRPC5 protein, human; C112021:Trpc5 protein, mouse; C503500:Trpc5 protein, rat
keywords: Calcium Imaging; Calcium Influx; Channel Gating; Ion Channels; Patch Clamp; Signal Transduction; TRP Channels