Channel proteins are hydrophilic.
They form pores or channels through the cell membrane, allowing the passage of water-soluble molecules and ions that cannot cross the hydrophobic lipid bilayer.
The interior of a channel protein is lined with hydrophilic amino acids, creating a pathway for water and other polar molecules to move through.
In contrast, the exterior of the channel protein is typically hydrophobic, interacting with the hydrophobic tails of the phospholipid molecules in the membrane.
This unique structure allows channel proteins to act as selective gates, controlling the movement of specific molecules across the cell membrane.
Examples of channel proteins include:
* **Aquaporins:** These proteins facilitate the transport of water across the cell membrane.
* **Ion channels:** These proteins allow the passage of specific ions, such as sodium, potassium, calcium, and chloride.