Rat brain expresses a heterogeneous family of calcium channels.
AUTOR(ES)
Snutch, T P
RESUMO
We describe the isolation and characterization of several rat brain cDNAs that are homologous to the alpha 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 approximately 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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=53906Documentos Relacionados
- Rat brain serotonin receptors in Xenopus oocytes are coupled by intracellular calcium to endogenous channels.
- Localization and functional properties of a rat brain alpha 1A calcium channel reflect similarities to neuronal Q- and P-type channels.
- Structural characterization of a heterogeneous family of rat brain mRNAs.
- Interactions among calcium compartments in C6 rat glioma cells: involvement of potassium channels.
- The aquaporin family of molecular water channels.