The three-dimensional structure of the potassium channelprovided a rationale for the selectivity of potassium ions and therejection of sodium ions. Which of the following is the basis forthe ability of the potassium channel to discriminate between thesetwo ions?
The sodium ion is too small to pass through the channel.
The opening of the channel is structurally arranged such thatpotassium ions can bind, but is too small for sodium ions.
A restriction in the channel allows for potassium ions to beresolvated by protein ligands but is too large to effectivelyresolvate sodium ions.
The restriction of the channel desolvates sodium ions but notpotassium ions.
