Conserved gating elements in TRPC4 and TRPC5 channels

• Main Authors: Abdulmughni, A. (Author), Beck, A. (Author), Cavalié, A. (Author), Dettmer, V. (Author), Flockerzi, V. (Author), Helms, V. (Author), Jusoh, S.A (Author), Philipp, S.E (Author), Sell, T. (Author), Speicher, T. (Author), Stoerger, C. (Author), Wissenbach, U. (Author), Zhu, M.X (Author)
• Format: Article
• Language: English
• Subjects: Activation analysis; Amino acid sequence; Amino Acid Substitution; Amino acids; Animals; article; biotinylation; Calcium; Calcium Imaging; Calcium Influx; carboxy terminal sequence; Cell death; cell viability; channel gating; Channel Gating; controlled study; C-terminal sequences; Current-voltage relationship; electrophysiology; genetic transfection; HEK293 Cells; human; human cell; Humans; Ion Channel Gating; Ion Channels; membrane permeability; Mice; Models, Molecular; Mutation, Missense; Non-selective cation channels; nucleotide sequence; Open conformation; Patch Clamp; Peptide Mapping; Phosphoinositides; priority journal; promoter region; protein domain; protein protein interaction; Protein Structure, Secondary; Protein Structure, Tertiary; Proteins; Rats; sequence alignment; sequence homology; Signal Transduction; Signaling cascades; site directed mutagenesis; transient receptor potential channel 4; transient receptor potential channel 5; Trans-membrane domains; TRP Channels; TRPC Cation Channels; voltage gated potassium channel
• Online Access: View Fulltext in Publisher; View in Scopus

 TRPC4 and TRPC5 proteins share 65% amino acid sequence identity and form Ca2+-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 Ca2+ 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. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.