Cloning of Fugu rubripes rubripes Sodium Channels

We were able to clone the partial sodium channel cDNAs from puffer fish, Fugu rubripes rubripes brain. 1. Three types of CDNA clones, pfBNal, pfBNa2 and pfBNa3, could be obtained from a puffer fish brain CDNA library. 2. The amino acid sequences derived from the nucleotide sequences of pfBNal and pfBNa2 contained sequences for the voltage sensor in segment 4, and pfBNa2 had a sequence for the ion-selective filter in the short segment (SS) 2 domain on each repeat and a sequence for the channel inactivation between repeat III and repeat IV. The amino acid sequences derived from these two clones seemed similar to that of the tetrodotoxin-sensitive sodium channel, although it is thought that the puffer fish has a tetrodotoxin-resistant sodium channel. 3. Northern blot analysis indicated that the brain contained a mixture of mRNA having lengths ranging from 5,000-7,000 nucleotides. The heart and skeletal muscles contained two distinct species of mRNA with about 6,000 and 1,500 nucleotides, respectively, while the liver had only one species with about 6,000 nucleotides. 4. Southern blot analysis with the puffer fish genomic DNA indicated that these two Na channels, pfBNal and pfBNa2, were alternatively spliced from the same gene and that the length of the gene encoding puffer fish Na channel was more than 30 kb. The puffer fish seems not to have any compact gene in this case.

ナトリウムチャンネル

クローニング

Tetrodotoxin

アミノ酸配列