CALMODULIN INTERACTS WITH C-TERMINAL REGION OF TRPC6

L. Grycova, B. Holakovska, J. Teisinger

Department of Protein Structures, Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, Praha 4, 142 20

The transient receptor potential channel TRPC6 is a non-selective cation channel involved in regulation of calcium levels in eukaryotic cells (including sensory receptor cells) in response to external signals. Calmodulin (CaM) is a ubiquitously expressed Ca²⁺-binding protein that serves as an important mediator of Ca²⁺-dependent regulation of the TRPC6 channel. One CaM binding site has been identified within the C-tail of TRPC6.

In this project we mapped in detail the CaM and inositol (1,4,5)-triphosphate receptor binding (CIRB) domain in the C-terminal region of mouse TRPC6 (801-878) capable of interacting with CaM using in vitro binding assays. Besides we used a set of positively charged amino acid residues Arg852, Lys856, Arg864 and Lys859/Arg860, and a hydrophobic residue Ile857 placed in position 1 in consensus CaM binding motif 1-5-10. We replaced these amino acids with neutral alanine and investigated role of the residues in CaM binding to TRPC6 C-terminus using fluorescence anisotropy measurement. Participation of Ile857 could indicate a strong role of this conserved CaM binding motif.

This project was supported by Grant GAAV IAA600110701, GACR 301/10/1159, GACR P205/10/P308, project (No. H148), Centre of Neurosciences No. LC554 MSMT CR, Research project No. AV0Z.