Advanced Placement (AP) Biology Practice Exam

What type of receptor is a G-protein-linked receptor?

1. A receptor that operates independently of other proteins

2. A membrane receptor that interacts with a G-protein

3. A cytoplasmic receptor that directly binds DNA

4. A receptor solely found in the nucleus

The correct answer is: A membrane receptor that interacts with a G-protein

A G-protein-linked receptor, also known as a G-protein-coupled receptor (GPCR), is classified as a membrane receptor that interacts with a G-protein. These receptors are embedded in the cell membrane and play a critical role in cellular communication. When a ligand, such as a hormone or neurotransmitter, binds to the GPCR, it causes a conformational change in the receptor. This change allows the receptor to activate the associated G-protein, which then dissociates into its subunits. These subunits can subsequently interact with other proteins or enzymes in the cell to propagate the signal and initiate various intracellular responses. This type of signaling mechanism is essential for a wide range of physiological processes, including sensory perception, immune responses, and regulation of mood and behavior. The interaction with G-proteins is a hallmark of this receptor type, distinguishing it from receptors that function independently or those located in the cytoplasm or nucleus.