Golgi Apparatus Flashcards
(35 cards)
What is the golgi apparatus?
A stack of flattened membrane bound compartments
What are cisternae?
Flattened membrane bound sacks
What is the function of the golgi apparatus?
Protein modification and storage
What is the structure of the golgi apparatus?
Cis cisterna
Medial cisterna
Trans cisterna
What type of proteins are sorted and modified in the golgi apparatus?
Proteins destined to be secreted
What molecule is the golgi apparatus the major site of synthesis of?
carbohydrates
- Glycoproteins
- Proteoglycans
In what type of cells is the golgi apparatus prominent?
Secretory cells
- Goblet cells
Describe the process by which a protein leaves the ER and enters the golgi apparatus.
- Proteins are synthesised on the ER
- Fully and correctly folded proteins leave the ER in vesicles
- The vesicle is transported to the golgi apparatus
- Vesicles undergo homotypic fusion which result in VTCs
- When the VTCs reach the cis cisterna they fuse to its membrane
- ER proteins are retrieved from the golgi apparatus
What do proteins require in order for efficient export from the ER?
An exit signal
What protein coating on the vesicle interacts with the ER membrane causing the vesicle to bud off?
COPII
When do vesicles shed their COPII protein coat?
Once they have budded off the ER
What is homotypic fusion?
The fusing of alike vesicles to form VTCs
What is a VTC?
Vesicular tubular cluster
What does the fusion of VTCs to the cis cisterna result in?
Release of cargo into the cisterna
What mediates the release of cargo into the cisterna?
The decrease in pH ; the golgi apparatus is more acidic than the ER
What type of protein coating is on vesicles which bud from the golgi apparatus headed for the ER?
COPI
What type of proteins are retrieved from the golgi apparatus?
Proteins involved in ER budding
Resident ER membrane proteins
Describe the process by which proteins move through and out of the golgi apparatus.
- VTCs displace and becomes the cis golgi network
- The cis golgi network displaces and becomes the medial golgi network
- The medial golgi network displaces and becomes the trans golgi network
- Vesicles bud from the trans golgi network until it is all gone and is then replaced by the medial golgi network
Where does N-linked glycosylation occur?
In the ER
Where does O-linked glycosylation occur?
In the golgi apparatus
What happens during the oligosaccharide processing?
Various sugars are added and trimmed as the protein passes through the golgi apparatus
What oligosaccharide processing occurs in the cis cisterna?
Mannose trimming
What oligosaccharide processing occurs in the medial cisterna?
Mannose trimming
N-acetyl glucosamine addition
What oligosaccharide processing occurs in the trans cisterna?
Galactose addition
N-acetylneuraminic acid addition
