Diversity of Voltage-Gated Sodium Channels in the Ascidian Larval Nervous System

To gain insight into the origin of the molecular diversity of voltage-gated sodium channels (NaVs), a putative sodium channel gene (TuNa2) was cloned from the protochordate ascidian. TuNa2 showed two unusual features in its primary structure; (1) lysine in the P-region of the third repeat, a critica...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 2000-08, Vol.275 (2), p.558-564
Main Authors: Nagahora, Hitoshi, Okada, Toshiaki, Yahagi, Naoya, Chong, Jayhong Andrew, Mandel, Gail, Okamura, Yasushi
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Ascidia
ascidian
Base Sequence
bFGF
DNA Primers
Ion Channel Gating
ion selectivity
Larva - metabolism
Molecular Sequence Data
motor neuron
Nervous System - growth & development
Nervous System - metabolism
Rats
Sequence Homology, Amino Acid
sodium channel
Sodium Channels - chemistry
Sodium Channels - genetics
Urochordata - growth & development
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Summary:To gain insight into the origin of the molecular diversity of voltage-gated sodium channels (NaVs), a putative sodium channel gene (TuNa2) was cloned from the protochordate ascidian. TuNa2 showed two unusual features in its primary structure; (1) lysine in the P-region of the third repeat, a critical site determining ion selectivity, was changed to glutamic acid, predicting that the ionic permeability would not be rigidly sodium-selective (2) the III-IV linker, determinant of fast inactivation, was only weakly conserved. In contrast with a pan-neuronally expressed NaV (TuNa1), expression of TuNa2 was confined to subsets of neurons including motor neurons, suggesting that TuNa2 plays specialized roles in electrical activities unique to these neurons. Basic FGF, a neural inducer in the ascidian embryo, induces TuNa2 RNA expression in the ectodermal cells at lower doses than that required for TuNa1 gene expression. Thus, two types of NaV may play distinct roles and their gene expressions are controlled by distinct mechanisms.
ISSN:0006-291X
1090-2104
DOI:10.1006/bbrc.2000.3290