What sequence of cellular compartments do newly synthesized GABA receptor subunits travel through to reach the cell surface?

• A. Endosome, Golgi complex, and lysosome
• B. Rough endoplasmic reticulum, Golgi complex, and secretory vesicle
• C. Rough endoplasmic reticulum, endosome, and Golgi complex
• D. Golgi complex, rough endoplasmic reticulum, and secretory vesicle

Answer: (B)

Newly synthesized GABA receptor subunits follow a specific sequence of cellular compartments to reach the cell surface, and the correct sequence begins in the rough endoplasmic reticulum. This organelle is involved in the synthesis of membrane proteins and secretory proteins, making it the initial site for the assembly of GABA receptor subunits. After synthesis, these proteins are then transported to the Golgi complex for further processing, modification, and sorting. The Golgi apparatus plays a critical role in the maturation of proteins and directs them to their respective destinations.

Following their processing in the Golgi complex, the GABA receptor subunits are packaged into secretory vesicles. These vesicles transport the proteins to the plasma membrane, where the receptors can be inserted and can perform their function as neurotransmitter receptors. This pathway is essential for ensuring that newly synthesized proteins reach the cell surface correctly and in a timely manner, which in turn supports effective synaptic transmission in neuronal communication.

The other sequences suggested involve compartments that do not align with the typical biosynthetic pathway for membrane proteins destined for the cell surface. For instance, lysosomes are not involved in moving proteins to the cell surface but instead are responsible for degradation. Similarly, moving from the Golgi complex back to