Investigation of Ligand Binding in the Transmembrane Region of Ion Channel TRPA1 via Mutation and Calcium Influx Assay.

Abstract

TRPA1 is the founding member of the ‘ankyrin repeat’ (TRPA) class of proteins. Ankyrin repeats are small (approximately 34 residue), repeating motifs creating an intracellular domain. They are not found exclusively in the TRPA family, but the large number of repeats, and therefore the large size of the intracellular domain, is the hallmark feature of the TRPA class. Homologs and paralogs are found across the animal spectrum, from drosophila to humans. In mammals, it is modulated by temperature (activated by cold), as well as a wide variety of small molecule activators and inhibitors. Of clinical importance, TRPA1 is implicated in paradoxical pain. This research project has aimed to better understand the intermembrane space interactions for an array of small hydrophobic modulators: which chemical motifs are involved and/or most important, and where they interact with the protein. Understanding how and where modulators bind in the transmembrane region has been an ongoing challenge. Since several compounds that activate TRPA1 also activate other TRP family channels (Menthol and TRPM8, for instance), understanding this in TRPA1 may be applicable to other TRP family proteins, and indeed other proteins.