scholarly journals Control of Slc7a5 sensitivity by the voltage-sensing domain of Kv1 channels

2020 ◽  
Author(s):  
Nazlee Sharmin ◽  
Shawn M. Lamothe ◽  
Victoria A. Baronas ◽  
Grace Silver ◽  
Yubin Hao ◽  
...  
Keyword(s):  
Amino Acid ◽  
Ion Channels ◽  
Functional Outcomes ◽  
Accessory Proteins ◽  
Expression Systems ◽  
Voltage Sensing ◽  
Voltage Dependent ◽  
Heterologous Expression Systems ◽  
Underlying Mechanisms ◽  
Voltage Sensing Domain

ABSTRACTMany voltage-dependent ion channels are regulated by accessory proteins, although the underlying mechanisms and consequences are often poorly understood. We recently reported a novel function of the amino acid transporter Slc7a5 as a powerful regulator of Kv1.2 voltage-dependent activation. In this study, we report that Kv1.1 channels are also regulated by Slc7a5, albeit with different functional outcomes. In heterologous expression systems, Kv1.1 exhibits prominent current enhancement (‘disinhibition’) with holding potentials more negative than −120 mV. Disinhibition of Kv1.1 is strongly attenuated by shRNA knockdown of endogenous Slc7a5. We investigated a variety of chimeric combinations of Kv1.1 and Kv1.2, demonstrating that exchange of the voltage-sensing domain controls the sensitivity and response to Slc7a5. Overall, our study highlights additional Slc7a5-sensitive Kv1 subunits, and demonstrates that features of Slc7a5 sensitivity can be swapped by exchanging voltage-sensing domains.IMPACT STATEMENTThe voltage-sensing mechanism of a subfamily of potassium channels can be powerfully modulated in unconventional ways, by poorly understood regulatory partners.

scholarly journals Control of Slc7a5 sensitivity by the voltage-sensing domain of Kv1 channels

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Shawn M Lamothe ◽  
Nazlee Sharmin ◽  
Grace Silver ◽  
Motoyasu Satou ◽  
Yubin Hao ◽  
...  
Keyword(s):  
Functional Outcomes ◽  
Accessory Proteins ◽  
Expression Systems ◽  
Voltage Sensing ◽  
Disinhibition Effect ◽  
Channel Inhibition ◽  
Voltage Dependent ◽  
Specific Position ◽  
Heterologous Expression Systems ◽  
Voltage Sensing Domain

Many voltage-dependent ion channels are regulated by accessory proteins. We recently reported powerful regulation of Kv1.2 potassium channels by the amino acid transporter Slc7a5. In this study, we report that Kv1.1 channels are also regulated by Slc7a5, albeit with different functional outcomes. In heterologous expression systems, Kv1.1 exhibits prominent current enhancement ('disinhibition') with holding potentials more negative than −120 mV. Knockdown of endogenous Slc7a5 leads to larger Kv1.1 currents and strongly attenuates the disinhibition effect, suggesting that Slc7a5 regulation of Kv1.1 involves channel inhibition that can be reversed by supraphysiological hyperpolarizing voltages. We investigated chimeric combinations of Kv1.1 and Kv1.2, demonstrating that exchange of the voltage-sensing domain controls the sensitivity and response to Slc7a5, and localize a specific position in S1 with prominent effects on Slc7a5 sensitivity. Overall, our study highlights multiple Slc7a5-sensitive Kv1 subunits, and identifies the voltage-sensing domain as a determinant of Slc7a5 modulation of Kv1 channels.

scholarly journals Structural mechanism of voltage-dependent gating in an isolated voltage-sensing domain

2014 ◽  
Vol 21 (3) ◽  
pp. 244-252 ◽  
Author(s):  
Qufei Li ◽  
Sherry Wanderling ◽  
Marcin Paduch ◽  
David Medovoy ◽  
Abhishek Singharoy ◽  
...  
Keyword(s):  
Voltage Sensing ◽  
Structural Mechanism ◽  
Voltage Dependent ◽  
Voltage Sensing Domain

scholarly journals Structural Mechanism of Voltage-Dependent Gating in an Isolated Voltage-Sensing Domain

2013 ◽  
Vol 104 (2) ◽  
pp. 196a
Author(s):  
Qufei Li ◽  
Sherry Wanderling ◽  
Marcin Paduch ◽  
David Medovoy ◽  
Carlos Villalba-Galea ◽  
...  
Keyword(s):  
Voltage Sensing ◽  
Structural Mechanism ◽  
Voltage Dependent ◽  
Voltage Sensing Domain

scholarly journals Galanin receptors in GtoPdb v.2021.2

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Andrew L. Gundlach ◽  
Philip J. Ryan
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Heterologous Expression ◽  
Expression Systems ◽  
Endogenous Peptides ◽  
Heterologous Expression Systems ◽  
Galanin Receptors ◽  
Amidated Peptide

Galanin receptors (provisional nomenclature as recommended by NC-IUPHAR [57]) are activated by the endogenous peptides galanin and galanin-like peptide. Human galanin is a 30 amino-acid non-amidated peptide [52]; in other species, it is 29 amino acids long and C-terminally amidated. Amino acids 1-14 of galanin are highly conserved in mammals, birds, reptiles, amphibia and fish. Shorter peptide species (e.g. human galanin-1-19 [21] and porcine galanin-5–29 [170]) and N-terminally extended forms (e.g. N-terminally seven and nine residue elongated forms of porcine galanin [22, 170]) have been reported. More recently, the newly-identified peptide, spexin (SPX), has been reported to activate human GAL2 and GAL3 (but not GAL1) receptors in heterologous expression systems; and to alter GAL2/3 receptor-related behaviours in animals [89].

scholarly journals Galanin receptors in GtoPdb v.2021.3

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Andrew L. Gundlach ◽  
Philip J. Ryan
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Heterologous Expression ◽  
Expression Systems ◽  
Endogenous Peptides ◽  
Heterologous Expression Systems ◽  
Galanin Receptors ◽  
Amidated Peptide

Galanin receptors (provisional nomenclature as recommended by NC-IUPHAR [57]) are activated by the endogenous peptides galanin and galanin-like peptide. Human galanin is a 30 amino-acid non-amidated peptide [52]; in other species, it is 29 amino acids long and C-terminally amidated. Amino acids 1-14 of galanin are highly conserved in mammals, birds, reptiles, amphibia and fish. Shorter peptide species (e.g. human galanin-1-19 [21] and porcine galanin-5-29 [170]) and N-terminally extended forms (e.g. N-terminally seven and nine residue elongated forms of porcine galanin [22, 170]) have been reported. More recently, the newly-identified peptide, spexin (SPX), has been reported to activate human GAL2 and GAL3 (but not GAL1) receptors in heterologous expression systems; and to alter GAL2/3 receptor-related behaviours in animals [89].

scholarly journals Voltage-dependent motion of the catalytic region of voltage-sensing phosphatase monitored by a fluorescent amino acid

2016 ◽  
Vol 113 (27) ◽  
pp. 7521-7526 ◽  
Author(s):  
Souhei Sakata ◽  
Yuka Jinno ◽  
Akira Kawanabe ◽  
Yasushi Okamura
Keyword(s):  
Plasma Membrane ◽  
Catalytic Activity ◽  
Amino Acid ◽  
Conformational Changes ◽  
Unnatural Amino Acid ◽  
Voltage Sensor ◽  
Voltage Sensing ◽  
Cytoplasmic Region ◽  
Voltage Dependent ◽  
Voltage Gated Ion Channels

The cytoplasmic region of voltage-sensing phosphatase (VSP) derives the voltage dependence of its catalytic activity from coupling to a voltage sensor homologous to that of voltage-gated ion channels. To assess the conformational changes in the cytoplasmic region upon activation of the voltage sensor, we genetically incorporated a fluorescent unnatural amino acid, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap), into the catalytic region of Ciona intestinalis VSP (Ci-VSP). Measurements of Anap fluorescence under voltage clamp in Xenopus oocytes revealed that the catalytic region assumes distinct conformations dependent on the degree of voltage-sensor activation. FRET analysis showed that the catalytic region remains situated beneath the plasma membrane, irrespective of the voltage level. Moreover, Anap fluorescence from a membrane-facing loop in the C2 domain showed a pattern reflecting substrate turnover. These results indicate that the voltage sensor regulates Ci-VSP catalytic activity by causing conformational changes in the entire catalytic region, without changing their distance from the plasma membrane.

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