Distribution and functional characterization of human Nav1.3 splice variants
| Autor: | P. E. Kroeger, W. Choi, R. A. Davis-Taber, C. B. Putman, Connie R. Faltynek, R. Thimmapaya, C. S. Surowy, Torben R. Neelands, M. Gopalakrishnan, V. E. Scott, J. Packer, W. Niforatos |
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| Rok vydání: | 2005 |
| Předmět: |
Gene isoform
Central Nervous System Protein subunit Xenopus Molecular Sequence Data Nerve Tissue Proteins Biology Sodium Channels Membrane Potentials Exon NAV1.3 Voltage-Gated Sodium Channel Animals Humans Protein Isoforms splice Amino Acid Sequence RNA Messenger G alpha subunit Base Sequence General Neuroscience Sodium channel Alternative splicing Cell Membrane Brain biology.organism_classification Molecular biology Rats Alternative Splicing Protein Subunits Spinal Cord Oocytes Female Sodium Channel Blockers |
| Zdroj: | The European journal of neuroscience. 22(1) |
| ISSN: | 0953-816X |
| Popis: | The focus of the present study is the molecular and functional characterization of four splice variants of the human Nav1.3 alpha subunit. These subtypes arise due to the use of alternative splice donor sites of exon 12, which encodes a region of the alpha subunit that resides in the intracellular loop between domains I and II. This region contains several important phosphorylation sites that modulate Na+ channel kinetics in related sodium channels, i.e. Nav1.2. While three of the four Nav1.3 isoforms, 12v1, 12v3 and 12v4 have been previously identified in human, 12v2 has only been reported in rat. Herein, we evaluate the distribution of these splice variants in human tissues and the functional characterization of each of these subtypes. We demonstrate by reverse transcriptase-polymerase chain reaction (RT-PCR) that each subtype is expressed in the spinal cord, thalamus, amygdala, cerebellum, adult and fetal whole brain and heart. To investigate the functional properties of these different splice variants, each alpha subunit isoform was cloned by RT-PCR from human fetal brain and expressed in Xenopus oocytes. Each isoform exhibited functional voltage-dependent Na+ channels with similar sensitivities to tetrodotoxin (TTX) and comparable current amplitudes. Subtle shifts in the V 1/2 of activation and inactivation (2-3 mV) were observed among the four isoforms, although the functional significance of these differences remains unclear. This study has demonstrated that all four human splice variants of the Nav1.3 channel alpha subunit are widely expressed and generate functional TTX-sensitive Na+ channels that likely modulate cellular excitability. |
| Databáze: | OpenAIRE |
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