COMPARISON OF C-TERMINAL SEGMENTS OF TRPV ION CHANNEL FAMILY MEMBERS AND THEIR INTERACTIONS WITH CALMODULIN

B. Holakovska, L. Grycova, J. Teisinger

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

TRPV ion channels belong to vanilloid subfamily of transient receptor potential channels (TRPs). These channels are ubiquitously expressed in all eukaryotic cells and are involved in many cellular processes like transduction of sensory signals and regulation of Ca²⁺ and Mg²⁺ homeostasis. [1]

TRPV1 and TRPV2 fall within the so called thermoTRPs. TRPV5 is a rather distinct member of TRPV subfamily and features quite different properties then the rest of this subfamily. It is strictly Ca²⁺ selective and involved in renal Ca²⁺ absorption/reabsorption. [2]

It is known that TRP channels are regulated by calmodulin (CaM) in calcium dependent manner via binding to their intracellular termini. [3; 4]

In our project we identified calmodulin binding sites on the C-termini of TRPV1 (686–837) [5], TRPV2 (654-683) and TRPV5 (587-616) [3]. These sites correspond to the consensus CaM binding motifs with conserved hydrophobic residues in positions 1-8-14 in TRPV1 and 1-5-10 in TRPV2 and TRPV5. Interestingly, the middle hydrophobic residue in the motif is exchanged for a charged residue in TRPV1 and TRPV2, indicating that these binding sites may be extraordinary. Site directed mutagenesis experiments further revealed that basic residues within these sites may play a crucial role in TRPV channels binding to CaM.

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.

[1] B. Nilius, G. Owsianik, T. Voets, Embo J 27 (2008), 2809-16

[2] J. Vriens, G. Appendino, B. Nilius, Mol Pharmacol 75 (2009), 1262-79

[3] B. Holakovska, L. Grycova, J. Bily, J. Teisinger, Amino Acids 40 (2011) 741-8

[4] E. Friedlova, L. Grycova, B. Holakovska, J. Silhan, H. Janouskova, M. Sulc, V. Obsilova, T. Obsil, J. Teisinger, Neurochem Int 56 (2010), 363-6

[5] L. Grycova, Z. Lansky, E. Friedlova, V. Obsilova, H. Janouskova, T. Obsil, J. Teisinger, Biochem Biophys Res Commun 375 (2008), 680-3