Question

In an HIV-infected cell producing HIV virus particles, the viral glycoprotein is expressed on the plasma membrane. How do the viral glycoproteins get to the plasma membrane?

A) They are synthesized on ribosomes on the plasma membrane.
B) They are synthesized by ribosomes in the rough ER, and arrive at the plasma membrane in the membrane of secretory vesicles.
C) They are synthesized on free cytoplasmic ribosomes, and then inserted into the plasma membrane.
D) They are synthesized by ribosomes in the rough ER, secreted from the cell, and inserted into the plasma membrane from the outside.
E) They are synthesized by ribosomes on the HIV viral membrane, which fuses with the plasma membrane from inside the cell.

Answer 1

HIV viral glycoproteins are synthesized and modified in the rough ER and Golgi apparatus. They reach the plasma membrane via vesicles that fuse with the plasma membrane, integrating the glycoproteins into it.

Step-by-step explanation:

The glycoproteins of HIV get to the plasma membrane via a cellular process involving the rough endoplasmic reticulum (RER) and the Golgi apparatus. Glycoproteins are initially synthesized by ribosomes in the rough ER. While in the ER, these proteins can be modified, such as by the addition of carbohydrates. After synthesis, these proteins are packaged into vesicles that bud from the ER and then fuse with the cis face of the Golgi apparatus. As the proteins move through the Golgi, they undergo further modifications. Finally, vesicles containing the fully processed glycoproteins bud off from the trans face of the Golgi and are transported to the plasma membrane. Upon fusion of these vesicles with the plasma membrane, the glycoproteins become an integral part of the plasma membrane.