How does Gly99 contribute to the gating of potassium channels?

Gly99 plays a crucial role in the gating mechanism of potassium channels by acting as a molecular hinge in response to various stimuli. This glycine residue is significant due to its flexible structure, which permits conformational changes that are essential when the channel transitions between open and closed states. In particular, glycine's small size contributes to a flexible region in the protein, allowing for the movement required to change the channel's conformation, thus enabling or blocking the passage of ions through the channel in response to alterations in voltage or ligand binding.

The other options do not accurately describe Gly99's role. It does not primarily function to store energy for channel opening, nor does it specifically strengthen the channel structure in a manner that influences gating. While selective ion passage is a key feature of potassium channels, it is the overall structure and selectivity filter that contribute to this function, rather than Gly99 itself being responsible for this property.