Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
The transitional endoplasmic reticulum (ER) is a region of the ER that specializes in the final steps of protein and lipid synthesis, including packaging these molecules into transport vesicles.
Related terms
Rough ER: This is another region of the endoplasmic reticulum where protein synthesis occurs, characterized by its rough appearance due to ribosomes attached to its surface.
Smooth ER: This part of the endoplasmic reticulum is involved in lipid synthesis and detoxification processes. It lacks ribosomes, giving it a smooth appearance.
A small structure within a cell, consisting of fluid enclosed by a lipid bilayer. Vesicles can deliver proteins throughout the cell or even outside it.