Question

Sodium and potassium ion channels have several negatively charged residues at the entry to the channel. On what basis do K+ channels specifically select for K+ ions? (In other words, why dont K+ channels enable Na+ ions to cross the membrane?)

 

-ionic radius, Na+ is to small

-energy cost, it is to energetically costly to dehydrate Na+

-charge, Na is slightly more electronegative than K and does not interact with the channel carbonyl groups

-charge, Na is slightly less electronegative than K and does not interact with the channel carbonyl groups

-ionic radius, Na+ is too big

Answer 1

energy cost, it is too energetically costly to dehydrate Na+

ionic radius, Na+ is too small