Helps stabilize protein in membrane k ion channel

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Helps stabilize protein in membrane.
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K + Ion Channel Homotetrameric protein. Ion pore made between the four monomers. Each monomer is made of 2 transmembrane  helices, 1 pore helix and a cytosolic tail. Selectivity Filter – formed from the backbone carbonyl Oxygens from the loops connecting pore helix to the inner transmembrane helix. The structure is stabilized by the packing of residues from the loop into the pore helix. Figure 12.10 Fig 12.9
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Potassium Channel Tetramer
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Potassium Channel Tetramer
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K + Channel: Pore Helix and Filter
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How is the channel selective for K + ? The protein acts as surrogate Water K (OH 2 ) 8 + = hydration shell (8 H 2 O needed to stabilize K + ) Within the K + Ion Channel only : Resolvation Energy ~ Desolvation Energy Na (OH 2 ) 6 + = hydration shell (6 H 2 O needed to stabilize Na + ) Within the K + Ion Channel only : Resolvation Energy <<< Desolvation Energy Rapid ion flow through the selectivity filter is facilitated by ion-ion repuslion, with one ion pushing the next ion through the channel
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How is the channel selective for K + ? The protein acts as surrogate Water K (OH 2 ) 8 + = hydration shell (8 H 2 O needed to stabilize K + ) Within the K + Ion Channel only :
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