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Evolution of voltage-gated Na(+) channels.
1Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697-4025, USA. agoldin@uci.edu
The Journal of Experimental Biology
|March 22, 2002
Summary
Voltage-gated sodium channels are crucial for electrical excitability across species. Their evolutionary history reveals a single origin, with distinct diversification in mammals and invertebrates.
Area of Science:
- Neuroscience
- Molecular Biology
- Evolutionary Biology
Background:
- Voltage-gated sodium channels (NaV) are essential for electrical excitability in diverse species.
- They belong to a superfamily including K+, Ca2+, and cyclic-nucleotide-gated channels.
- Mammals possess nine functional NaV channel genes, with potential for a tenth.
Purpose of the Study:
- To investigate the evolutionary origins and diversification of voltage-gated sodium channels.
- To understand the phylogenetic relationships and chromosomal localization of mammalian NaV channel genes.
- To compare NaV channel gene evolution in vertebrates and invertebrates.
Main Methods:
- Phylogenetic analysis of NaV channel genes.
- Comparative genomics across species.
- Chromosomal mapping of mammalian NaV channel genes.
Main Results:
- Mammalian NaV genes form five distinct phylogenetic branches, located on four chromosomes.
- Four mammalian branches likely arose from chromosomal duplications associated with Hox gene clusters near vertebrate origins.
- Invertebrates show two NaV gene branches, with only one confirmed to encode functional channels.
Conclusions:
- Vertebrate and invertebrate NaV channels likely evolved from a single primordial channel.
- Independent evolutionary trajectories shaped NaV channel repertoires in vertebrates and invertebrates.
- Chromosomal duplications played a significant role in the expansion of NaV channel genes in mammals.