Open AccessModulation of activation and inactivation by Ca2+ and 2-APB in the pore of an archetypal TRPM channel from Nematostella vectensis
Author(s) -
Frank Kühn,
Mathis Winking,
Cornelia Kühn,
Daniel C. Hoffmann,
Andreas Lückhoff
Publication year - 2017
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/s41598-017-07652-4
Subject(s) - trpm2 , biophysics , microbiology and biotechnology , gating , subfamily , transient receptor potential channel , chemistry , biology , biochemistry , receptor , gene
The archetypal TRPM2-like channel of the sea anemone Nematostella vectensis is gated by ADPR like its human orthologue but additionally exhibits properties of other vertebrate TRPM channels. Thus it can help towards an understanding of gating and regulation of the whole subfamily. To elucidate further the role of Ca 2+ as a co-factor of ADPR, we exploited 2-aminoethyl diphenylborinate (2-APB), previously shown to exert either inhibitory or stimulatory effects on diverse TRPM channels, or both in a concentration-dependent manner. 2-APB in high concentrations (1 mM) induced large, non-inactivating currents through nv TRPM2. In lower concentrations (≤0.5 mM), it prevented the fast current inactivation typical for nv TRPM2 stimulated with ADPR. Both these effects were rapidly reversed after wash-out of 2-APB, in contrast to a considerable lag time of their onset. A detailed analysis of nv TRPM2 mutants with modified selectivity filter or reduced ADP-ribose sensitivity revealed that the actions of 2-APB depend on its access to the pore which is enhanced by channel opening. Moreover, access of Ca 2+ to the pore is decisive which again depends on the open state of the channel. We conclude that separate regulatory processes by Ca 2+ on the pore can be discriminated with the aid of 2-APB.