Question

Regarding Golgi specialized functions:

a) Discuss the Golgi’s roll in ‘trafficking” cell components (include discussing of the ‘two faces’)

b)What role does dolichol phosphate play in glycosylation?

c)Does glycosylation occur before or after a protein is folded?

Answer 1

a) Discuss the Golgi’s role in ‘trafficking” cell components (include discussing of the ‘two faces’)

Golgi’s role in ‘trafficking” cell components

The cis Golgi network and trans Golgi network play an important role in sorting of cell components. They are received at the cis face and released at the trans face by the organelle.

The cell components received at the cis face will arrive in clusters of fused vesicles and the fused vesicles migrate along microtubules through vesicular-tubular cluster. The contents delivered into the lumen of the cis face cisterna. The cell components then entered into the trans face.

Thr molecules are then modified such as cleavage of oligosaccharide side chains, addition of fatty acids or phosphate groups (phosphorylation), the removal of monosaccharides.

Finally, the cell components are packaged into vesicles at the trans face and targetted to their destinations.

b)What role does dolichol phosphate play in glycosylation?

Dolichol play important role in the co-translational modification of proteins such as N-glycosylation in the form of dolichol phosphate.

This N-linked protein glycosylation assembled at the membrane of the endoplasmic reticulum and serves as a carrier in this biosynthetic pathway.

c)Does glycosylation occur before or after a protein is folded?

Glycosylation occur after a protein is folded. Proteins fold correctly when they undergo glycosylation. N-linked glycosylation occurs when the protein sequence Asn-X-Thr or Asn-X-Ser is reached. X, which helps to adhere between cells.

Gycosylation on proteins act as useful markers for the movement of cell components from the ER and through the Golgi cisternae.