Exam 3- The Golgi Apparatus

Question 1

How is the Golgi organized?

Answer 1

The golgi is split between 3 compartments; cis medial and trans
and one network near the PM; the Trans-Golgi network.
Made of membrane enclosed sacs called CISTERNAE

Question 2

what is CISTERNAE

Answer 2

the membrane enclosed sacs making the Golgi

Question 3

-What’s the name of the process that mediates the traffic of vesicles from one organelle to the next in the secretory pathway?

Answer 3

Vesicular traffic

Question 4

Are there any signals that determine the export of Integral Membrane Proteins from the ER to the Golgi? If so, what are they?

Answer 4

Di-hydrophobic- for membrane proteins

Di-acidic- for luminal and GPI anchored proteins

Question 5

What targets soluble proteins to be exported form the ER to the Golgi?

Answer 5

No specific targeting signal, follows default pathway, goes from ER to Golgi through vesicles.

Question 6

What’s a RETRIEVAL sequence?

Answer 6

Theses sequences make sure the proteins go back to ER from the ERGIC or the Cys-Golgi

Question 7

What’s the amino acid sequence that acts as a Retrieval Sequence for soluble proteins?

Answer 7

KDEL

Question 8

What’s the amino acid sequence that acts as a Retrieval Sequence for integral membrane proteins?

Answer 8

KKXX

Question 9

How are N-linked oligosaccharides processed in the Golgi?

Answer 9

As N-Linked protein is made in the lumen of the ER from dolichol, 2 enzymes remove the terminal 3 glucoses. Causeing the tail to go from 14 to 11 residues.
Once this glycoprotein is in the golgi a series of modifications are done.

Question 10

What’s the role played by the phosphorylation of mannose residues?

Answer 10

Signal that targets the protein to the lysosome.

Question 11

Which lipids are synthesized in the Golgi? and are also only found on the lumenal side of the glogi

Answer 11

Sphingomyelin - not a glycerol derivative

Glycolipids- initial addition of the glucose occurs on the cytosolic side but further addition of other sugars occurs only on the luminal side and prevents further flips.

Question 12

what are the 3 mechanisms to transport from the golgi to the cell surface?

Answer 12

Direct transport from trans-golgi network to PM. - Constitutive soluble proteins

Using intermediate recycling endosomes

Using the regulated sec pathway in response to environmental signals- Hormones, neurotransmitters and digestive enzymes.