Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

This Article Full Text Full Text (PDF, 241K) PPT slides of all figures Alert me when this article is cited Citation Map Services Email this article Similar articles in this journal Similar articles in PubMed Alert me to new content in the JGP Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Crary, J. I. Articles by Zimmerman, A. L. Search for Related Content PubMed PubMed Citation Articles by Crary, J. I. Articles by Zimmerman, A. L. Social Bookmarking                            What's this?

Original Article

^a Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, Rhode Island 02912
Department of Molecular Pharmacology, Physiology and Biotechnology, Box G-B329, Brown University, Providence, RI 02912.(401) 863-1222

anita_zimmerman{at}brown.edu

We previously found that native cyclic nucleotide–gated (CNG) cation channels from amphibian rod cells are directly and reversibly inhibited by analogues of diacylglycerol (DAG), but little is known about the mechanism of this inhibition. We recently determined that, at saturating cGMP concentrations, DAG completely inhibits cloned bovine rod (Brod) CNG channels while only partially inhibiting cloned rat olfactory (Rolf) channels (Crary, J.I., D.M. Dean, W. Nguitragool, P.T. Kurshan, and A.L. Zimmerman. 2000. J. Gen. Phys. 116:755–768; in this issue). Here, we report that a point mutation at position 204 in the S2–S3 loop of Rolf and a mouse CNG channel (Molf) found in olfactory epithelium and heart, increased DAG sensitivity to that of the Brod channel. Mutation of this residue from the wild-type glycine to a glutamate (Molf G204E) or aspartate (Molf G204D) gave dramatic increases in DAG sensitivity without changing the apparent cGMP or cAMP affinities or efficacies. However, unlike the wild-type olfactory channels, these mutants demonstrated voltage-dependent gating with obvious activation and deactivation kinetics. Interestingly, the mutants were also more sensitive to inhibition by the local anesthetic, tetracaine. Replacement of the position 204 glycine with a tryptophan residue (Rolf G204W) not only gave voltage-dependent gating and an increased sensitivity to DAG and tetracaine, but also showed reduced apparent agonist affinity and cAMP efficacy. Sequence comparisons show that the glycine at position 204 in the S2–S3 loop is highly conserved, and our findings indicate that its alteration can have critical consequences for channel gating and inhibition.

Key Words: rod • olfactory • heart • diacylglycerol • tetracaine

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				A. D. Wei, A. Butler, and L. Salkoff KCNQ-like Potassium Channels in Caenorhabditis elegans: CONSERVED PROPERTIES AND MODULATION J. Biol. Chem., June 3, 2005; 280(22): 21337 - 21345. [Abstract] [Full Text] [PDF]

				S. L. McCabe, D. M. Pelosi, M. Tetreault, A. Miri, W. Nguitragool, P. Kovithvathanaphong, R. Mahajan, and A. L. Zimmerman All-trans-retinal Is a Closed-state Inhibitor of Rod Cyclic Nucleotide-gated Ion Channels J. Gen. Physiol., April 26, 2004; 123(5): 521 - 531. [Abstract] [Full Text] [PDF]

				Q. Leng, R. W. Mercier, B.-G. Hua, H. Fromm, and G. A. Berkowitz Electrophysiological Analysis of Cloned Cyclic Nucleotide-Gated Ion Channels Plant Physiology, February 1, 2002; 128(2): 400 - 410. [Abstract] [Full Text] [PDF]

				J. I. Crary, D. M. Dean, W. Nguitragool, P. T. Kurshan, and A. L. Zimmerman Mechanism of Inhibition of Cyclic Nucleotide-Gated Ion Channels by Diacylglycerol J. Gen. Physiol., December 1, 2000; 116(6): 755 - 768. [Abstract] [Full Text] [PDF]

Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents