How Does a Plasma Membrane Protein Become Imbedded in the Membrane

Question

How does a plasma membrane protein become imbedded in the membrane?
A)Ribosomes attach to the plasma membrane and translation of the peptide occurs directly on the PM.
B)Ribosomes enter the endoplasmic reticulum and make the proteins within the ER.
C)Once the signal peptide is translated, the ribosome complex is escorted to the PM, translation continues and the peptide is inserted through a pore in the membrane.
D)Once the signal peptide is translated, the ribosome complex is escorted to the ER, translation continues and the peptide is inserted through a pore in the membrane.
E)Once completed, the protein is escorted to the PM and a chaperone protein pushes it in.

Accepted Answer

Proteins that are destined to be embedded within the plasma membrane are synthesized on ribosomes that are attached to the endoplasmic reticulum (ER) membrane. As the protein is synthesized, it is translocated into the ER lumen through a pore in the membrane. Once completed, the protein is transported to the plasma membrane where it becomes embedded. Therefore, choice D is the correct answer.