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Rat brain expresses a heterogeneous family of calcium channels

Snutch, Terry P. and Leonard, John P. and Gilbert, Mary M. and Lester, Henry A. and Davidson, Norman (1990) Rat brain expresses a heterogeneous family of calcium channels. Proceedings of the National Academy of Sciences of the United States of America, 87 (9). pp. 3391-3395. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:SNUpnas90

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Abstract

We describe the isolation and characterization of several rat brain cDNAs that are homologous to the 1 subunit of heart and skeletal muscle dihydropyridine-sensitive Ca channels. Northern blot analysis of 32 cDNAs shows that they can be grouped into four distinct classes (A, B, C, and D), each corresponding to a distinct hybridization pattern of brain mRNAs. Southern blot and DNA sequencing suggest that each class of cDNA represents a distinct gene or gene family. In the regions sequenced, the rat brain class C and D gene products share 75% amino acid identity with the rabbit skeletal muscle Ca channel. In addition, the class C polypeptide is almost identical to the rabbit cardiac Ca channel (97% identity). In contrast, the rat brain class A and B cDNAs are more distantly related to dihydropyridine-sensitive Ca channels (47-64% amino acid identity) and to the brain class C and D genes (51-55% amino acid identity). To examine the functional significance of the isolated brain cDNAs, hybrid depletion experiments were performed in Xenopus oocytes. Antisense oligonucleotides against class A and B cDNAs each partially inhibited, and a class C oligonucleotide almost fully inhibited, the expression of Ba current in rat brain mRNA injected oocytes; but none of the oligonucleotides affected the expression of voltage-gated Na or K conductances. The clone characterization and sequencing results demonstrate that a number of distinct, yet related, voltage-gated Ca-channel genes are expressed in the brain. The antisense oligonucleotide experiments specifically show that one or several of the Ca-channel classes are related to the Ca channels observed in rat brain mRNA injected oocytes.


Item Type:Article
Additional Information:© 1990 by the National Academy of Sciences. Contributed by Norman Davidson, February 21, 1990. We are grateful to Steve Dubel for technical assistance and to Ellis et al. (11) for providing the rabbit Ca-channel probe. We also thank Mike White for the suggestion of using niflumic acid to block the oocyte C1 current. This work was supported by grants from the Medical Research Council of Canada (T.P.S.) and National Institutes of Health Grants NS-26432 (J.P.L.), GM-10991 (N.D.), and GM-29836 (H.A.L.). During the earlier phases of this work, T.P.S. was supported by an American Heart Association Fellowship, Greater Los Angeles Affiliate, at the California Institute of Technology. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Subject Keywords:cDNA cloning; hybrid arrest; dihydropyridine receptor
Record Number:CaltechAUTHORS:SNUpnas90
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:SNUpnas90
Alternative URL:http://dx.doi.org/10.1073/pnas.87.9.3391
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8754
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:13 Sep 2007
Last Modified:14 Nov 2014 19:20

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