總結(jié) |
Voltage-gated sodium channels (NaV) are essential for the generation of actionpotentials and for cell excitability.1 To date, nine NaV α subunits have been cloned and named NaV1.1-NaV1.9.2,3 Mammalian sodium channels are heterotrimers, composed of a central, pore-forming α subunit and two auxiliary β-subunits (NaVβ-subunit).4The NaV β-subunit gene family consists of four members: β1 (SCN1B), β2 (SCN2B), β3 (SCN3B), and β4 (SCN4B) having type I topology, containing an extracellular amino-terminus, a single transmembrane segment, and an intracellular carboxyl-terminus.They modulate channel gating, assembly, and cell surface expression in heterologous cell systems.5NaV β-subunits are cell adhesion molecules of the Ig superfamily, which interact with extracellular matrix, transmembrane signaling, and cell adhesion molecules.5In the adult central nervous system and heart, sodium channels are associate with β1- β4 subunits, whereas in adult skeletal muscle they are associate only with the β1 subunit.4,5This association appears to be a late event in sodium channel biosynthesis.6Expression of β2-subunits increases in sensory neurons following nerve injury. β2 deficient mice develop less mechanical allodynia in compare to wild type mice, suggesting a role for β2 subunit in pain sensation. 7
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Western blot analysis of rat brain membranes under reducing (lanes 1 and 2) or non-reducing (lanes 3 and 4) conditions:<sup>*</sup>
1,3. Anti-Na β 2 antibody ( AMM06540G), (1:200).
2,4. Anti-Na β 2 antibody, preincubated with the control peptide antigen.
<sup>*</sup> Na β 2 is disulfide-linked to the α subunit of voltage-gated Na<sup>+</sup> channels (Schmidt, J.W., and Catterall, W.A. (1986) Cell 46, 437.)
Expression of Na β 2 in mouse cerebellum
Immunohistochemical staining of mouse cerebellum using Anti-Na β 2 antibody ( AMM06540G). A. Na β 2 channel (red) appears in Purkinje cells (vertical arrows) and in small cells in the molecular layer (horizontal arrows, Mol). B. Staining of Purkinje nerve cells with mouse anti-calcium binding protein (CBD28k, green) demonstrates the restriction of Na β 2 to cell bodies. C, Confocal merge of Na β 2 and CBD28k.
Expression of Na β 2 in rat cerebellum
Immunohistochemical staining of rat cerebellum using Anti-Na β 2 antibody ( AMM06540G). A. Na β 2 channel (red) appears in Purkinje cells (horizontal arrows) and is distributed diffusely in the molecular layer (Mol). B. Staining of Purkinje nerve cells with mouse anti-calcium binding protein (CBD28k, green) demonstrates the restriction of Na β 2 to cell bodies. C. Confocal merge of Na β 2 and CBD28k.
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