Lecture 14: Intracellular trafficking

Question 1

What is the order of protein exocytic sequence?

Answer 1

RER -> SER -> (COPII) Cis
Golgi -> Trans Golgi ->(Clathrin) Secretory vesicle -> Exocytosis

Question 2

What is the acronym that helps us remember COP proteins

Answer 2

COP’s investigation went
II steps forward and I step
backwards.

-COP 1: towards ER
-COP II: cell membrane

Question 3

______________and ___________ are protein coats

Answer 3

caveolin and clathrin*caveolin linked to transcytosis

Question 4

Endoscopes and lysosomes are made from _______________

Answer 4

golgi

Question 5

____________________: Common 1 in every 250 individuals
Low Density Lipoproteins (LDL):
* Part of the transport system for cholesterol, needed by cells for membrane.
* Acquired through receptor-mediated endocytosis.
* Presentation:
* Xanthomas (cholesterol deposits in skin or
tendons like Achilles or wrist).
* Xanthelasma (cholesterol deposits in eyelids).
* Corneal arcus (deposits cause a white or gray
ring around iris)

Answer 5

Familial Hypercholesterolemia

Question 6

Hypercholestrolemia can be homozyous or heterozygous. Can you explain what this means in terms of this disease?

Answer 6

Heterozygous -> Heart attack before 50 (men) or 60 (women)
* Homozygous -> High probability of cardiac death before 20 yo.

Question 7

What happens in hypercholesterolemia?

Answer 7

• Mutations in the LDL receptor can lead to non-binding or failure to internalize the receptor.
• Less LDL internalized -> More LDL in circulation -> High Cholesterol in plasma -> Endothelial deposits -> Macrophage ingestion -> Foamy cell formation -> Atherosclerosis

Question 8

______________ is a process that moves large molecules and waste out of a cell and into the extracellular space. It’s a type of bulk transport, which is a process that moves large numbers of molecules in and out of a cell

Answer 8

Exocytosis

Question 9

_________ is where different models for profession and transport occur

Answer 9

Golgi apparatus.

Question 10

__________ is involved in retrograde flow of membrane and return of proteins

Answer 10

COPI

Question 11

___________ glycosylated proteins tags them for end-some and lysosomal transport

Answer 11

phosphorylation of mannose in N linked glycosylated protein tags

Question 12

________________
Part of Lysosomal Storage Diseases (LSD).
* Presents in infancy with hypotonia, developmental delay, limited
mobility, clubfeet, and thickened skin.
* Frequent bone and joint abnormalities and umbilical and inguinal hernia.
* Narrow airway and thoracic abnormalities can lead to respiratory
infections and insufficiency. Often fatal in first decade.

Answer 12

I cell disease

Mucolipidosis

Question 13

In Mucolipidosis or I cell disease what happens

Answer 13

Failure to phosphorylate mannose residues in lysosomes so lysosomes re secreted instead of transported

Question 14

What are two two sides of the plasma membrane?

Answer 14

-Basolateral membrane: (end-some sorting)
-Apical membrane:

*There are specific signals that determine which side proteins or molecules go to

Question 15

Maturation from vacuole to __________ occurs int eh regulated secretory pathway

Answer 15

secretory granule

Question 16

In terms of secretory granules what is the movement?

Answer 16

Kinesins transport to the + end
of microtubules.

• Dyneins transport to the – end of
  microtubules.

Question 17

What is the granule and vesicle fusion mediated by

Answer 17

• SNARE complex: Synaptobrevin, Syntaxin, SNAP-25.
• Synaptotagmin mediates fusion (controlled by [Ca++].

Question 18

Fusion regulators ____________. They regulate vesicular traffic and SNARE assembly.

Answer 18

RAB proteins

Question 19

Alterations in Rabs proteins reduce _________________

Answer 19

adipose cell response to insulin ->
Predisposition to insulin resistance.