Role of the α-Kinase Domain in Transient Receptor Potential Melastatin 6 Channel and Regulation by Intracellular ATP
Copyright policy )Role of the α-Kinase Domain in Transient Receptor Potential Melastatin 6 Channel and Regulation by Intracellular ATP
Transient receptor potential melastatin 6 (TRPM6) plays an essential role in epithelial Mg(2+) transport. TRPM6 and its closest homologue, TRPM7, both combine a cation channel with an alpha-kinase domain. However, the role of this alpha-kinase domain in TRPM6 channel activity remains elusive. The aim of this study was to investigate the regulation of TRPM6 channel activity by intracellular ATP and the involvement of its alpha-kinase domain. We demonstrated that intracellular Na- and Mg-ATP decreased the TRPM6 current in HEK293 cells heterogeneously expressing the channel, whereas Na-CTP or Na-GTP had no effect on channel activity. Whole cell recordings in TRPM6-expressing HEK293 cells showed that deletion of the alpha-kinase domain prevented the inhibitory effect of intracellular ATP without abrogating channel activity. Mutation of the conserved putative ATP-binding motif GXG(A)XXG (G1955D) in the alpha-kinase domain of TRPM6 inhibited the ATP action, whereas this effect remained preserved in the TRPM6 phosphotransferase-deficient mutant K1804R. Mutation of the TRPM6 autophosphorylation site, Thr(1851), into either an alanine or an aspartate, resulted in functional channels that could still be inhibited by ATP. In conclusion, intracellular ATP regulates TRPM6 channel activity via its alpha-kinase domain independently of alpha-kinase activity.
- Radboud University Nijmegen Medical Centre Netherlands
- Radboud University Nijmegen Netherlands
Models, Molecular, Patch-Clamp Techniques, IGMD 9: Renal disorder, Amino Acid Motifs, Molecular Sequence Data, NCMLS 2: Metabolism, transport and motion, NCMLS 3: Growth and differentiation, TRPM Cation Channels, UMCN 5.4: Renal disorders, NCMLS 5: Membrane transport and intracellular motility, Cell Line, Protein Structure, Tertiary, Substrate Specificity, Electrophysiology, Adenosine Triphosphate, Mutation, Humans, Amino Acid Sequence, Protein Kinases
Models, Molecular, Patch-Clamp Techniques, IGMD 9: Renal disorder, Amino Acid Motifs, Molecular Sequence Data, NCMLS 2: Metabolism, transport and motion, NCMLS 3: Growth and differentiation, TRPM Cation Channels, UMCN 5.4: Renal disorders, NCMLS 5: Membrane transport and intracellular motility, Cell Line, Protein Structure, Tertiary, Substrate Specificity, Electrophysiology, Adenosine Triphosphate, Mutation, Humans, Amino Acid Sequence, Protein Kinases
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