Golgi Apparatus Structure and Function

Golgi Apparatus

Overview

• The Golgi apparatus is the next destination for proteins after they exit the endoplasmic reticulum (ER).

• The Golgi is often referred to as the "Golgi stack" due to its structure resembling a stack of pancakes.

• It consists of flattened, membrane-bound compartments called cisternae stacked on top of each other.

Structure

The Golgi apparatus is divided into three main regions:

1. Cis-Golgi Network (CGN)

• The CGN is the region of the Golgi closest to the ER.

• It serves as the receiving area for transport vesicles that bud off from the ER.

• These vesicles fuse with the CGN, delivering their protein cargo.

2. Medial-Golgi Network (MGN)

• The MGN is the middle region of the Golgi.

• It's the primary site for protein processing and modification.

• Various modifications can occur here, such as glycosylation (addition of sugar molecules).

3. Trans-Golgi Network (TGN)

• The TGN is the region of the Golgi closest to the plasma membrane.

• It's the final processing and packaging area for proteins.

• Proteins are sorted and packaged into transport vesicles that bud off from the TGN.

• These vesicles then travel to their final destinations within the cell.

Function Summary

• CGN: Receives transport vesicles from the ER.

• MGN: Performs protein processing and modification (e.g., glycosylation).

• TGN: Packages and sorts proteins into transport vesicles for delivery to their final destinations (like a post office).