Which Features Allow the KcsA Channel to Selectively Transport K⁺

question 2

Multiple Choice

Which features allow the KcsA channel to selectively transport K⁺?
(I) The entrance of the channel contains hydrophobic residues which forces the removal of waters of hydration.
(II) It is attracted to the entrance of the channel via electrostatic interactions.
(III) The "selectivity filter" involves a narrowing of the channel,allowing only dehydrated K⁺ access.
(IV) As K⁺ is transported through the channel it interacts with −C=O groups from the protein.

• A)I,II,III,IV
• B)II,III,IV
• C)II,III
• D)III,IV
• E)I,III

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