Question

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

G-protein-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

G-protein-coupled receptors should be described by the function of coupling with intracellular GTP-binding proteins, and are characterized by having seven transmembrane domains.

Step-by-step explanation:

When matching the class of cell-surface receptor with the best description of its function, G-protein-coupled receptors should be paired with the description: must be coupled with intracellular monomeric GTP-binding proteins. This matches option C in the initial list provided. G-protein-coupled receptors bind a ligand and then activate a membrane protein known as a G-protein. This activated G-protein can then interact with an ion channel or an enzyme in the membrane to transmit a signal into the cell. Notably, all G-protein-coupled receptors share a common feature of having seven transmembrane domains, although each receptor has unique extracellular domains and G-protein-binding sites specifically designed to interact with certain ligands and G-proteins.

Answer 2

G-protein-coupled receptors (GPCRs) have seven transmembrane domains and activate a G-protein when a ligand binds, leading to a cascade of intracellular events. The correct match for their function is that all receptors of this class are polypeptides with seven transmembrane domains. So, the correct answer is D.

Step-by-step explanation:

To match the class of cell-surface receptor with the best description of its function, we look at G-protein-coupled receptors (GPCRs). These receptors are known for having seven transmembrane domains, and they serve an essential role in signal transduction. When a ligand binds to a GPCR, it activates an associated G-protein, which then either affects an ion channel or an enzyme within the cell membrane. All G-protein-coupled receptors possess their unique extracellular domains and specific G-protein-binding sites.

Based on this information, the correct match for the function of G-protein-coupled receptors is:

• G-protein-coupled receptors - D. All receptors of this class are polypeptides with seven transmembrane domains.