Little is known about the structure of the C terminus of the human cardiac voltage-gated sodium channel alpha subunit (SCN5A), but disease-linked mutations within this 244-amino acid intracellular region of the channel have marked effects on channel inactivation. Here we report a structural analysis of the C-terminal tail of the cardiac Na(+) channel that sheds new light on mechanisms that control its inactivation gating. Homology modeling of the SCN5A C terminus predicts predominant alpha-helical structure (six helices) in the proximal half of this intracellular tail but little structure in the distal half. Circular dichroism of isolated and purified C terminus supports this prediction. Whole cell and single channel patch clamp recordings of wild type and mutant alpha subunits co-expressed with the hbeta(1) subunit in HEK 293 cells indicate that truncation of the distal, nonstructured, C terminus (L1921stop mutant) reduces current density but does not affect channel gating (n = 6). In contrast, truncation of the sixth helix containing a concentration of positively charged residues along with the distal C terminus (S1885stop mutant) also reduces current density but, in addition, has profound and selective effects on inactivation (no effect on activation). Channel availability is shifted (-11 +/- 0.6 mV), and there is a 10-fold increase in the percentage of channels that burst (fail to inactivate) during prolonged depolarization (0.025% S1885stop (n = 7) versus 0.0028% wild type (n = 9), p < 0.005). These results suggest that the charged structured region of the SCN5A C terminus plays a major role in channel inactivation, stabilizing the inactivated state.

Cormier, J., Rivolta, I., Tateyama, M., Yang, A., Kass, R. (2002). Secondary structure of the human cardiac Na+ channel C terminus: evidence for a role of helical structures in modulation of channel inactivation. THE JOURNAL OF BIOLOGICAL CHEMISTRY, 277(11), 9233-9241 [10.1074/jbc.M110204200].

Secondary structure of the human cardiac Na+ channel C terminus: evidence for a role of helical structures in modulation of channel inactivation

Rivolta, I;
2002

Abstract

Little is known about the structure of the C terminus of the human cardiac voltage-gated sodium channel alpha subunit (SCN5A), but disease-linked mutations within this 244-amino acid intracellular region of the channel have marked effects on channel inactivation. Here we report a structural analysis of the C-terminal tail of the cardiac Na(+) channel that sheds new light on mechanisms that control its inactivation gating. Homology modeling of the SCN5A C terminus predicts predominant alpha-helical structure (six helices) in the proximal half of this intracellular tail but little structure in the distal half. Circular dichroism of isolated and purified C terminus supports this prediction. Whole cell and single channel patch clamp recordings of wild type and mutant alpha subunits co-expressed with the hbeta(1) subunit in HEK 293 cells indicate that truncation of the distal, nonstructured, C terminus (L1921stop mutant) reduces current density but does not affect channel gating (n = 6). In contrast, truncation of the sixth helix containing a concentration of positively charged residues along with the distal C terminus (S1885stop mutant) also reduces current density but, in addition, has profound and selective effects on inactivation (no effect on activation). Channel availability is shifted (-11 +/- 0.6 mV), and there is a 10-fold increase in the percentage of channels that burst (fail to inactivate) during prolonged depolarization (0.025% S1885stop (n = 7) versus 0.0028% wild type (n = 9), p < 0.005). These results suggest that the charged structured region of the SCN5A C terminus plays a major role in channel inactivation, stabilizing the inactivated state.
Articolo in rivista - Articolo scientifico
Protein Structure, Secondary; Humans; Molecular Sequence Data; Circular Dichroism; Amino Acid Sequence; Sodium Channels; NAV1.5 Voltage-Gated Sodium Channel
English
2002
277
11
9233
9241
none
Cormier, J., Rivolta, I., Tateyama, M., Yang, A., Kass, R. (2002). Secondary structure of the human cardiac Na+ channel C terminus: evidence for a role of helical structures in modulation of channel inactivation. THE JOURNAL OF BIOLOGICAL CHEMISTRY, 277(11), 9233-9241 [10.1074/jbc.M110204200].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/274353
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