Molecular and Functional Characterization of the Melastatin-related Cation Channel TRPM3

Proteins of the mammalian TRP (transient receptor potential) family form a heterogenous group of cation channels important for cellular Ca2+ signaling and homeostasis. Here we present the full-length sequence of TRPM3, a member of the melastatin-like subfamily (TRPM) of TRP channels. TRPM3 expressio...

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Bibliographic Details
Published in:The Journal of biological chemistry 2003-06, Vol.278 (24), p.21493-21501
Main Authors: Grimm, Christian, Kraft, Robert, Sauerbruch, Sophie, Schultz, Günter, Harteneck, Christian
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Base Sequence
Blotting, Northern
Blotting, Western
Calcium - metabolism
Calcium Channels - chemistry
Calcium Channels - metabolism
Cations
Cell Line
Cell Membrane - metabolism
Cesium - pharmacology
Cloning, Molecular
DNA, Complementary - metabolism
Homeostasis
Humans
Ion Channels - genetics
Ion Channels - metabolism
Ion Channels - physiology
Kidney - metabolism
Kinetics
Manganese - pharmacology
Membrane Proteins - chemistry
Membrane Proteins - metabolism
Microscopy, Confocal
Molecular Sequence Data
Neoplasm Proteins
Patch-Clamp Techniques
Plasmids - metabolism
Reverse Transcriptase Polymerase Chain Reaction
Sequence Homology, Amino Acid
Signal Transduction
Spectrometry, Fluorescence
Tissue Distribution
Transfection
TRPM Cation Channels
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Summary:Proteins of the mammalian TRP (transient receptor potential) family form a heterogenous group of cation channels important for cellular Ca2+ signaling and homeostasis. Here we present the full-length sequence of TRPM3, a member of the melastatin-like subfamily (TRPM) of TRP channels. TRPM3 expression was found in human kidney and brain. HEK293 cells transiently transfected with TRPM3 showed a constitutive Ca2+ and Mn2+ entry. Whole-cell patch clamp experiments confirmed the spontaneous activity of TRPM3 and revealed permeability ratios PCa/PNa of 1.57 and PNa/PCs of 0.75. In cell-attached patches, spontaneous inward and outward currents were observed. At negative membrane potentials and in the presence of either 140 mm Cs+, 140 mm Na+, or 100 mm Ca2+ in the pipette solution, the single channel conductance levels were 133, 83, and 65 pS, respectively. The Ca2+ entry in TRPM3-expressing HEK293 cells increased during treatment with hypotonic extracellular solution. The reduction of extracellular osmolarity was accompanied by cell swelling, suggesting volume-regulated activity of TRPM3. From its function and expression in human kidney, we propose a role of TRPM3 in renal Ca2+ homeostasis.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M300945200