Functional characteristics of TRPC4 channels expressed in HEK 293 cells |
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Authors: | Tae Sik Sung Min Ji Kim Soojin Hong Jae-Pyo Jeon Byung Joo Kim Ju-Hong Jeon Seon Jeong Kim Insuk So |
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Institution: | (1) Center for Bio-Artificial Muscle and Department of Physiology, Seoul National University College of Medicine, Seoul, 110-799, Korea;(2) Center for Bio-Artificial Muscle and Department of Biomedical Engineering, Hanyang University, Seoul, 133-791, Korea |
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Abstract: | The classical type of transient receptor potential (TRPC) channel is a molecular candidate for Ca2+-permeable cation channels in mammalian cells. Because TRPC4 and TRPC5 belong to the same subfamily of TRPC, they have been
assumed to have the same physiological properties. However, we found that TRPC4 had its own functional characteristics different
from those of TRPC5. TRPC4 channels had no constitutive activity and were activated by muscarinic stimulation only when a
muscarinic receptor was co-expressed with TRPC4 in human embryonic kidney (HEK) cells. Endogenous muscarinic receptor appeared
not to interact with TRPC4. TPRC4 activation by GTPγS was not desensitized. TPRC4 activation by GTPγS was not inhibited by
either Rho kinase inhibitor or MLCK inhibitor. TRPC4 was sensitive to external pH with pK
a of 7.3. Finally, TPRC4 activation by GTPγS was inhibited by the calmodulin inhibitor W-7. We conclude that TRPC4 and TRPC5
have different properties and their own physiological roles.
These authors contributed equally to this work. |
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Keywords: | desensitization nonselective cation channel pH transient receptor potential channel TRPC4 TRPC5 |
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