Lecture 11: Golgi and Lysosomes-Function and Trafficking Flashcards Preview

BIOC 341 > Lecture 11: Golgi and Lysosomes-Function and Trafficking > Flashcards

Flashcards in Lecture 11: Golgi and Lysosomes-Function and Trafficking Deck (48)
Loading flashcards...
1

Golgi complex

  • Ordered series of flatten membrane stacks called cisternae 
  • Usually consist of 4-6 cisterna 
  • Each of the Golgi cisterna have unique protein (and lipid) composition 
  • Stacks are often connected by tubules to form a continuous organelle 
  • Located in the perinuclear region (around the nucleus) close to the centrisome 
  • Localization is maintained by microtubules 

2

Model of the Golgi Complex

3

Which stains can be used to indicate the different golgi compartments?

Trans face- Nucleoside diphosphate

Cis face- Osmium

TGN- Acid phosphatase

4

___ proteins cause coating with COPII in the golgi

Sec proteins

5

The ____ complex begins to build a coat 

Sec23/Sec24 

6

The ___ complex finishes the coat 

Sec13/31 

7

Coat proteins also help sequester ____

cargo receptors

8

9

In what 3 ways are cargo selected for inclusion in vesicles?

  • Export signals
  • Retention
  • Bulk flow

10

Export Signals

 Proteins to be transported have a export signal that allows selective packaging into transport vesicles

11

Retention

  • Proteins have a mechanism to be excluded form transport vesicles 

• Chaperone binding 

• Kin Recognition 

12

Bulk flow

– Some proteins get packaged simply because they are in the right place at the right time 

13

_____ also participates in decision about entry into COPII transport vesicles and ER exit 

  • The ER quality control apparatus
  • Most of the time this is a good thing to prevent inappropriately folded protein or subunits of unassembled complexes from reaching the cell surface 
    • Large amounts (up 90%) of the T-cell receptor, acetylcholine receptor are degraded and never reach the cell surface

14

15

In what case is the quality control machinery is too good?

– Cystic Fibrosis Transmembrane Regulator (CFTR) 

16

ER-derived transport vesicles fuse to form ____

vesicular tubular clusters (VTC)

17

VTC’s form by ____ membrane fusion

homotypic

18

What happens when ER resident proteins get transported out of the ER? 

They are actively retrieved! 

– Soluble residents 

• KDEL sequence and receptor 

– Membrane bound residents 

• KKXX motif 

19

How does the KDEL receptor know when to bind and when to release KDEL-containing proteins? 

  • The interaction between the KDEL tetrapeptide and the KDEL receptor is pH sensitive. 
    •  The relatively acidic pH of the Golgi compartment permits the association of the KDEL tetrapeptide with the KDEL receptor 
    • The more neutral pH of the ER allows release (and prevents binding) 

20

The KDEL receptor binds to escaped KDEL protein in the ____

cis Golgi

21

ER-Golgi anterograde and retrograde traffic

22

_____ function to anchor and localize transport gesicles

Golgins

23

How do golgins do anchor and localize vesicles?

Through a rab interaction domain and a cytoskeletal interactor domain

24

What are the two models of intra-golgi transport?

  1. Vesicle transport model
  2. Cisternal maturation model

25

Vesicle transport model

26

Cisternal Maturation Model

27

Biochemical functions of the Golgi 

• Glycosylation 

– Modification of existing Nlinked sugars 

– O-linked glycosylation 

– Production of proteoglycans 

• Protein sorting 

• Sulfation 

– Specific tyrosine residues in proteins

28

Biochemical function of the cis golgi network

  • phopsphorylization of oligosaccharides on lysosomal proteins

29

biochemical functions of cis cisterna

  • removal of Man

30

Biochemical function of medial cisterna

  • removal of Man
  • addition of GlcNAc