Where Is the Ion Selectivity Filter Located, Considering the Quaternary

question 42

Multiple Choice

Where is the ion selectivity filter located, considering the quaternary structure of a representative, well-studied ion channel like K_CS?

• A) The outer vestibule of the channel, which is approximately 2 nm in diameter
• B) Adjacent to short helices and their neighboring residues, which form a box-like structure at the channel's extracellular face
• C) Within the central pore
• D) Within the lower pore
• E) By the inner helix, which predominantly forms the narrowest part of the channel structure

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