Lysine 1110 of TRPM2 is critical for channel activation

In this study, we investigated the functional role of lysine residue at position 1110 (K1110) in the membrane-proximal C-terminal region by site-directed mutagenesis. Substitution of the positive charged amino acid lysine (K1110) with neutral charged amino acid asparagine (K1110N) or negative charged amino acid glutamic acid (K1110E) generated mutants that failed to induce increase in free cytosolic calcium concentration ([Ca2+]i) not only by intracellular injection of chloride ion but also by H2O2 or ADPR. However, mutant generated by substitution of lysine with the same positive charged amino acid arginine (K1110R) displayed channel activity similar to wild-type TRPM2. Interestingly, in K1107N/K1110N double-point mutant, the impaired function of K1110N mutant in response to ADPR and H2O2, but not to chloride ion, was recovered. There were no changes in protein expression, membrane trafficking and oligomerization of the mutant channels. The extent of [Ca2+]i increase by H2O2 in TRPM2 mutants-expressing HEK cells was well correlated with the degree of susceptibility to H2O2–induced cell death. These results display a crucial role of a positive charged amino acid residue at position 1110 for TRPM2 channel activity.

Source: BJ Cell - August 19, 2013 Category: Biochemistry Authors: T Kim, J Hyun Nam, W Ahn, N Kim, H Ham, C Hong, J Nam, J Lee, S Huh, I So, S Joon Kim, D Song Tags: BJ Signal Source Type: research