Question

In regard to their subunit structure, how are K+, Na+, Ca2+, Cl- ion channels different?

Answer 1

Difference in interactions of selectivity filter with K+ compared to Na+ ions are significant. K+ ions and water molecules within the filter undergo concerted single file motion in which they translocate between adjacent sites within the filter on a nanosecond timescale. In contrast Na+ ions remain bound to site within the filter and do not exhibit translocation on nanosecond timescale.

Future entry of a K+ ion into the filter from the extracellular mouth is observed .whereas this does not occur for Na+ ions..K+ ions prefer to sit within a cage of eight oxygen atoms of the filter,Na+ ions prefer to interact with a ring of four oxygen atoms plus two water molecules .