Endocytosis 1+2- ES

Question 1

Under microscope- what is the phenotype of a Clathrin coated vesicle

Answer 1

Round vesicle, with rounded proteins surrounding the vesicle

Question 2

Roles of dynamin for 3 main endocytic processes- e.g clathrin.

Answer 2

3 main endocytic processes=
Clathrin, Caveolar, and RhoA.

Question 3

About Dynamin and its roles in endocytosis-
1. what is dynamin?
2. formation…
3. after vesicle to target membrane

Answer 3

1. Dynamin is a GTPase, allowing the hydrolysis of GTP into GDP. This is essential for vesicle formation
2. Dynamin hydrolysing GTP induces a mechanical force, used to constrict the pit -clathrin coated- helping budding of the vesicle
3. Recycling/ disassembly of the clathrin coat

Question 4

What is macropinocytosis?
(hint- break it down)

Answer 4

Type of endocytosis- what is that?
cellular process where cells engulf extracellular fluid, large particles and. macromolecules
- usually used to sample their environment and uptake nutrients and remove extracellular debris

Question 5

Application of Macropinocytosis for diseases
name them and describe how they use this.

Answer 5

This is a non-specific process.
. Some virus and bacterium have evolved to exploit the non-specificity to gain access to host cells.
. CANCER cells can upregulate the process to support their rapid growth, with extracellular nutrients

Question 6

phenotype of caveolae

Answer 6

small, flask shaped invaginations or vesicles

Question 7

Caveolae- mediated endocytosis
what is different about this than other endocytic processes

Answer 7

Allows cells to internalise specific molecules and receptors

Question 8

What type of endocytic process is directly involved in ‘regulation of cellular lipid metabolism and the internalisation of certain signalling receptors’
- focus on certain lipids, signalling molecules and proteins (cargo..)

Answer 8

Caveolae-mediated endocytosis

Question 9

(1) Caveolae signal transduce, due to a protein. (2) what is it called and what does it do?

Answer 9

Caveolin, which interacts with various signalling molecules and receptors.
helps compartmentalise and regulate signalling pathways, by organising signalling molecules with in the vesicles.

Question 10

(1)Mechanosensation and its (2) relation to Caveolae.

Answer 10

-mechanosensation= ability of cells to recognise mechanical forces (stretching or sheer force)
-Caveolae can alter their shape in response to physical cues, which alters specific response to stimuli.

Question 11

How does mechanosensing cells help cells?

Answer 11

protection against sheer stress, and mechanical forces (like blood flow)
Act as stress-responsive structures

Question 12

Mutations in Cav1 and Cav3 cause what?
and how to remember Cav protein

Answer 12

Muscle fragility, and some muscular dystrophy arise from it too
Cavin and Caveolins= caveolae proteins

Question 13

What does CIE mean

Answer 13

Clathrin independent endocytosis
can be caveolae, etc

Question 14

How do caveolae respond to membrane tension to stop blebbing

Answer 14

1-Caveolae respond to stress, which is how blebbing starts. in response to stress, Caveolae will endocytose to relieve tension

Question 15

What is blebbing=

Answer 15

when the cells surface starts to bulge due to stress, maybe too much intercellular force
blebbing helps= immune response, tissue development and cancer progression

Question 16

why does blebbing help cancer progression

Answer 16

Causing proteins, like caveolae (TMPs), to induce endocytosis
endocytosis is the uptake of large particles, in which this will help cancer progression

Question 17

What is the effect of GRAF1 on CIE

Answer 17

Regulates CIE, and any endocytosis that doesnt involve clathrin coated pits
*thought to do this by GRAF1-mediated regulation of ARF6

Question 18

Activation of ARF6 does what in the endocytotic pathway

Answer 18

It is crucial for the CIE pathway
*not Clathrin coated pits

Question 19

why does loss of GRAF1 increase invasiveness
GRAF1 acts as a tumour suppressor

Answer 19

GRAF1 regulates ARF6, ARF6 increases endocytosis in the CIE pathway= more nutrient uptake and large particles

Question 20

What role do peptide motifs have for protein-protein interactions

Answer 20

serve as recognition sites for other proteins, allowing binding and interactions with the protein containing motif
*signal transduction, protein trafficking and p-p interactions

Question 21

AP2- adaptor protein complex 2
role in which type of endocytosis?
Role in this endocytosis? (hint-cargo)
Structure and formation of the *Complex

Answer 21

1- Clathrin mediated endocytosis
2- Cargo selection and therefore formation of the vesicles/ coating too
3- Alpha, beta2, mu2, omega2

Question 22

Alpha protein in AP2, Role=

Answer 22

Recognises and binds to sorting signals or motifs on cargo molecules

Question 23

Beta2 protein on AP2, Role=

Answer 23

Stabilises the interaction between a-subunit and cargo proteins
helps assemble clathrin coat

Question 24

Mu2 protein on AP2, Role=

Answer 24

Cargo recognition and binding
interaction w/ a subunit and cargo molecules through motifs (specific**)

Question 25

Omega2 protein on AP2, Role=

Answer 25

Linking AP2 complex to clathrin
help form the clathrin coated vesicle

Question 26

roles of sorting signals in endocytic proteins- Tyrosine based, Di leucine, Ubiquitin etc

Answer 26

specific amino acid sequences or motifs within proteins
direct the intracellular trafficking and subcellular localisation
e.g= stay in specific compartment, transported and degredation

Question 27

motifs recognised by AP1, and what part of the AP1 or AP2 is the signal recognised

Answer 27

Tyrosine-based- lysosomes, basolateral somatodendritic domains

Dileucine based- Endo-lysosmal TMPs

Recognised by the Mu subunit of the AP1/2