Golgi Apparatus and ER — Role & Importance in Translation

Let's be honest, the only organelle that ever gets any recognition is the mitochondrion. I mean it's pretty great, but it's really not nearly as cool as the Golgi apparatus or the endoplasmic reticulum. Seriously… just look at those names.

Anyway. Everything about us, the way we look and act, is a product of our genes. And in order for our genes to have any effect, they need to be translated into proteins. Both the endoplasmic reticulum and the Golgi apparatus have very important roles in this process.

Endoplasmic Reticulum

The endoplasmic reticulum (ER) is divided into two parts: the rough ER and the smooth ER. Only the rough ER really plays a part in protein synthesis.

If you've already learned some basics about the ER, then you know that the rough part contains ribosomes which are responsible for translating pieces of mRNA into proteins. Once the protein is made, it can make its way into the lumen (inside) of the rough ER.

In the lumen, the protein is folded into a specific 3D structure which is necessary for it to work correctly. This is also where additional chemical groups like carbohydrates can be added to the protein structure. Then, the proteins can be transported to the cell membrane, or they can move to the Golgi apparatus for more processing.

Golgi Apparatus

You probably already know some things about the Golgi apparatus as well. In the Golgi, proteins are sorted and packaged based on function and final destination. The Golgi apparatus labels the protein so the cell knows where it's needed. Then, it uses its own membrane to form a vesicle around the protein which will transport it to that location. Without the Golgi apparatus, the cell would not know what to do with new proteins.

Rough ER and Golgi Apparatus (Translation)

The endoplasmic reticulum is where the bulk of the ribosomes that create proteins are stored. The rough part of the endoplasmic reticulum is rough because of all of the ribosomes on its surface.

mRNA is transported out of the nucleus and shipped over to the endoplasmic reticulum for protein synthesis. Sometimes the proteins are made inside of the endoplasmic reticulum and sometimes they are made on the outside of it.

The Golgi apparatus is responsible for packing and labeling proteins for transport. Proteins are big and can't easily move through a cell (and almost never through a membrane by themselves).

The Golgi apparatus will place labels on the proteins so that transport proteins can recognize them and take them to where they are needed in the cell. If the proteins are required for use outside of the cell, they will be packed into a vesicle and go through exocytosis.

(Video) Protein Trafficking

by ndsuvirtualcell

As proteins leave the ribosomes after translation, the rough ER takes them and modifies them. These proteins are then exported to the membrane of the cell.

The Golgi Apparatus is the FedEx of the cell world. It neatly packages, sorts, and modifies proteins that it gets from the endoplasmic reticulum. These proteins are either stored in the cell or secreted out.