Requirement for the N-terminal coiled-coil domain for expression and function, but not subunit interaction of, the ADPR-activated TRPM2 channel.
Transient receptor potential melastatin 2 (TRPM2) proteins form multiple-subunit complexes, most likely homotetramers, which operate as Ca2+-permeable, nonselective cation channels activated by intracellular ADP-ribose (ADPR) and oxidative stress. Each TRPM2 channel subunit is predicted to contain two coiled-coil (CC) domains, one in the N-terminus and the other in the C-terminus. Our recent study has shown that the C-terminal CC domain plays an important, but not exclusive, role in the TRPM2 channel assembly. This study aimed to examine the potential role of the N-terminal CC domain. Domain deletion dramatically reduced protein expression and abolished ADPR-evoked currents but did not alter the subunit interaction. Deletion of both CC domains strongly attenuated the subunit interaction, confirming that the C-terminal CC domain is critical in the subunit interaction. Glutamine substitutions into individual hydrophobic residues at positions a and d in the heptad repeats to disrupt the CC formation had no effect on protein expression, subunit interaction, or ADPR-evoked currents. Mutation of Ile(658) to glutamine, which did not perturb the CC formation, decreased ADPR-evoked currents without affecting protein expression, subunit interaction, or membrane trafficking. These results collectively suggest the requirement for the N-terminal CC domain for protein expression and function, but not subunit interaction, of the TRPM2 channel.
Mei
Zhu-Zhong
ZZ
Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS29JT, UK.
Jiang
Lin-Hua
LH
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D002460:Cell Line; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology*; D007668:Kidney / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D013329:Structure-Activity Relationship; D050053:TRPM Cation Channels / Q000737:chemistry* / Q000378:metabolism*
D021122:Protein Subunits; D050053:TRPM Cation Channels; C121934:TRPM2 protein, human; D000246:Adenosine Diphosphate Ribose