Question

Match the class of cell-surface receptor with the best description of its function.

ion-channel-coupled receptors ______
A. alter the membrane potential directly by changing the permeability of the plasma membrane
B. signal by opening and closing in a ligand-independent manner
C. must be coupled with intracellular monomeric GTP-binding proteins
D. all receptors of this class are polypeptides with seven transmembrane domains
E. discovered for their role in responding to growth factors in animal cells

Answer 1

Ion channel-linked receptors bind a ligand and open a channel through the membrane that allows specific ions to pass through. This is accomplished through a conformational change in the receptor's structure upon ligand binding.

Step-by-step explanation:

Ion channel-linked receptors bind a ligand and open a channel through the membrane that allows specific ions to pass through. To form a channel, this type of cell-surface receptor has an extensive membrane-spanning region. In order to interact with the double layer of phospholipid fatty acid tails that form the center of the plasma membrane, many of the amino acids in the membrane-spanning region are hydrophobic in nature. Conversely, the amino acids that line the inside of the channel are hydrophilic to allow for the passage of water or ions. When a ligand binds to the extracellular region of the channel, there is a conformational change in the protein's structure that allows ions such as sodium, calcium, magnesium, and hydrogen to pass through.