Potassium Channel: Difference between revisions

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====Voltage Sensor====

      Channel pore opening is dependent on the membrane voltage, a characteristic that is “sensed” by the <scene name='Potassium_Channel/Voltage_sensors_opening/6'>voltage sensor</scene>. The voltage sensor is comprised of <scene name='Potassium_Channel/Voltage_helices/3'>six helices</scene>, S0, S1, S2, S3, S4, & S5. Negatively charged amino acids in the sensor are either located in the <scene name='Potassium_Channel/Voltage_external/3'>external cluster</scene>, consisting of Glu 183 (in the [[2r9r]] structure) and Glu 226, or in the <scene name='Potassium_Channel/Voltage_internal/3'>internal cluster</scene> consisting of Glu 154, Glu 236, and Asp 259. The external cluster is exposed to solvent while the internal cluster is buried. **Phenylalanine 233** separates the external and internal clusters.<ref name="Long"/> The 7**positively charged residues** of the voltage sensor are located on the S4 helix. Lys 302 and Arg 305 **form hydrogen bonds** with the internal negative cluster while Arginines 287, 290, 293, 296 and 299 are **exposed to the extracellular solution**. When the voltage sensor is exposed to a strong negative electric field in the intracellular membrane, the positive gating charges shift inward with the α-carbon of Arg 290 shifting to interact with Phe 233. This shift effectively squeezes the pore shut, closing the intracellular-extracellular pathway. For a comparison see: The **Open** Channel vs. The **Closed** (1k4c like in 6c and D) Channel.<ref name="Long"/>

      Channel pore opening is dependent on the membrane voltage, a characteristic that is “sensed” by the <scene name='Potassium_Channel/Voltage_sensors_opening/6'>voltage sensor</scene>. The voltage sensor is comprised of <scene name='Potassium_Channel/Voltage_helices/3'>six helices</scene>, S0, S1, S2, S3, S4, & S5. Negatively charged amino acids in the sensor are either located in the <scene name='Potassium_Channel/Voltage_external/3'>external cluster</scene>, consisting of Glu 183 (in the [[2r9r]] structure) and Glu 226, or in the <scene name='Potassium_Channel/Voltage_internal/4'>internal cluster</scene> consisting of Glu 154, Glu 236, and Asp 259. The external cluster is exposed to solvent while the internal cluster is buried. <scene name='Potassium_Channel/Voltage_phe/2'>Phenylalanine 233</scene> separates the external and internal clusters.<ref name="Long"/> The 7**positively charged residues** of the voltage sensor are located on the S4 helix. Lys 302 and Arg 305 **form hydrogen bonds** with the internal negative cluster while Arginines 287, 290, 293, 296 and 299 are **exposed to the extracellular solution**. When the voltage sensor is exposed to a strong negative electric field in the intracellular membrane, the positive gating charges shift inward with the α-carbon of Arg 290 shifting to interact with Phe 233. This shift effectively squeezes the pore shut, closing the intracellular-extracellular pathway. For a comparison see: The **Open** Channel vs. The **Closed** (1k4c like in 6c and D) Channel.<ref name="Long"/>

      Overall, Potassium channels are remarkable structures that allow for near diffusion limit transfer of molecules with sub-angstrom specificity. Our understanding of the structure of Potassium Channels has opened up the potential for [[Pharmaceutical drugs|therapeutic intervention]] into Potassium channel related diseases.

Potassium Channel: Difference between revisions

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@@ Line 12: / Line 12: @@
 ====Voltage Sensor====
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Channel pore opening is dependent on the membrane voltage, a characteristic that is “sensed” by the <scene name='Potassium_Channel/Voltage_sensors_opening/6'>voltage sensor</scene>. The voltage sensor is comprised of <scene name='Potassium_Channel/Voltage_helices/3'>six helices</scene>, S0, S1, S2, S3, S4, & S5. Negatively charged amino acids in the sensor are either located in the <scene name='Potassium_Channel/Voltage_external/3'>external cluster</scene>, consisting of Glu 183 (in the [[2r9r]] structure) and Glu 226, or in the <scene name='Potassium_Channel/Voltage_internal/3'>internal cluster</scene> consisting of Glu 154, Glu 236, and Asp 259. The external cluster is exposed to solvent while the internal cluster is buried. **Phenylalanine 233** separates the external and internal clusters.<ref name="Long"/> The 7**positively charged residues** of the voltage sensor are located on the S4 helix. Lys 302 and Arg 305 **form hydrogen bonds** with the internal negative cluster while Arginines 287, 290, 293, 296 and 299 are **exposed to the extracellular solution**.  When the voltage sensor is exposed to a strong negative electric field in the intracellular membrane, the positive gating charges shift inward with the α-carbon of Arg 290 shifting to interact with Phe 233. This shift effectively squeezes the pore shut, closing the intracellular-extracellular pathway. For a comparison see: The **Open** Channel vs. The **Closed** (1k4c like in 6c and D) Channel.<ref name="Long"/>
+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Channel pore opening is dependent on the membrane voltage, a characteristic that is “sensed” by the <scene name='Potassium_Channel/Voltage_sensors_opening/6'>voltage sensor</scene>. The voltage sensor is comprised of <scene name='Potassium_Channel/Voltage_helices/3'>six helices</scene>, S0, S1, S2, S3, S4, & S5. Negatively charged amino acids in the sensor are either located in the <scene name='Potassium_Channel/Voltage_external/3'>external cluster</scene>, consisting of Glu 183 (in the [[2r9r]] structure) and Glu 226, or in the <scene name='Potassium_Channel/Voltage_internal/4'>internal cluster</scene> consisting of Glu 154, Glu 236, and Asp 259. The external cluster is exposed to solvent while the internal cluster is buried. <scene name='Potassium_Channel/Voltage_phe/2'>Phenylalanine 233</scene> separates the external and internal clusters.<ref name="Long"/> The 7**positively charged residues** of the voltage sensor are located on the S4 helix. Lys 302 and Arg 305 **form hydrogen bonds** with the internal negative cluster while Arginines 287, 290, 293, 296 and 299 are **exposed to the extracellular solution**.  When the voltage sensor is exposed to a strong negative electric field in the intracellular membrane, the positive gating charges shift inward with the α-carbon of Arg 290 shifting to interact with Phe 233. This shift effectively squeezes the pore shut, closing the intracellular-extracellular pathway. For a comparison see: The **Open** Channel vs. The **Closed** (1k4c like in 6c and D) Channel.<ref name="Long"/>
 &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Overall, Potassium channels are remarkable structures that allow for near diffusion limit transfer of molecules with sub-angstrom specificity. Our understanding of the structure of Potassium Channels has opened up the potential for [[Pharmaceutical drugs|therapeutic intervention]] into Potassium channel related diseases.