Endocytosis 1+2- ES Flashcards
Under microscope- what is the phenotype of a Clathrin coated vesicle
Round vesicle, with rounded proteins surrounding the vesicle
Roles of dynamin for 3 main endocytic processes- e.g clathrin.
3 main endocytic processes=
Clathrin, Caveolar, and RhoA.
About Dynamin and its roles in endocytosis-
1. what is dynamin?
2. formation…
3. after vesicle to target membrane
- Dynamin is a GTPase, allowing the hydrolysis of GTP into GDP. This is essential for vesicle formation
- Dynamin hydrolysing GTP induces a mechanical force, used to constrict the pit -clathrin coated- helping budding of the vesicle
- Recycling/ disassembly of the clathrin coat
What is macropinocytosis?
(hint- break it down)
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
Application of Macropinocytosis for diseases
name them and describe how they use this.
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
phenotype of caveolae
small, flask shaped invaginations or vesicles
Caveolae- mediated endocytosis
what is different about this than other endocytic processes
Allows cells to internalise specific molecules and receptors
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..)
Caveolae-mediated endocytosis
(1) Caveolae signal transduce, due to a protein. (2) what is it called and what does it do?
Caveolin, which interacts with various signalling molecules and receptors.
helps compartmentalise and regulate signalling pathways, by organising signalling molecules with in the vesicles.
(1)Mechanosensation and its (2) relation to Caveolae.
-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.
How does mechanosensing cells help cells?
protection against sheer stress, and mechanical forces (like blood flow)
Act as stress-responsive structures
Mutations in Cav1 and Cav3 cause what?
and how to remember Cav protein
Muscle fragility, and some muscular dystrophy arise from it too
Cavin and Caveolins= caveolae proteins
What does CIE mean
Clathrin independent endocytosis
can be caveolae, etc
How do caveolae respond to membrane tension to stop blebbing
1-Caveolae respond to stress, which is how blebbing starts. in response to stress, Caveolae will endocytose to relieve tension
What is blebbing=
when the cells surface starts to bulge due to stress, maybe too much intercellular force
blebbing helps= immune response, tissue development and cancer progression
why does blebbing help cancer progression
Causing proteins, like caveolae (TMPs), to induce endocytosis
endocytosis is the uptake of large particles, in which this will help cancer progression
What is the effect of GRAF1 on CIE
Regulates CIE, and any endocytosis that doesnt involve clathrin coated pits
*thought to do this by GRAF1-mediated regulation of ARF6
Activation of ARF6 does what in the endocytotic pathway
It is crucial for the CIE pathway
*not Clathrin coated pits
why does loss of GRAF1 increase invasiveness
GRAF1 acts as a tumour suppressor
GRAF1 regulates ARF6, ARF6 increases endocytosis in the CIE pathway= more nutrient uptake and large particles
What role do peptide motifs have for protein-protein interactions
serve as recognition sites for other proteins, allowing binding and interactions with the protein containing motif
*signal transduction, protein trafficking and p-p interactions
AP2- adaptor protein complex 2
role in which type of endocytosis?
Role in this endocytosis? (hint-cargo)
Structure and formation of the *Complex
1- Clathrin mediated endocytosis
2- Cargo selection and therefore formation of the vesicles/ coating too
3- Alpha, beta2, mu2, omega2
Alpha protein in AP2, Role=
Recognises and binds to sorting signals or motifs on cargo molecules
Beta2 protein on AP2, Role=
Stabilises the interaction between a-subunit and cargo proteins
helps assemble clathrin coat
Mu2 protein on AP2, Role=
Cargo recognition and binding
interaction w/ a subunit and cargo molecules through motifs (specific**)
Omega2 protein on AP2, Role=
Linking AP2 complex to clathrin
help form the clathrin coated vesicle
roles of sorting signals in endocytic proteins- Tyrosine based, Di leucine, Ubiquitin etc
specific amino acid sequences or motifs within proteins
direct the intracellular trafficking and subcellular localisation
e.g= stay in specific compartment, transported and degredation
motifs recognised by AP1, and what part of the AP1 or AP2 is the signal recognised
Tyrosine-based- lysosomes, basolateral somatodendritic domains
Dileucine based- Endo-lysosmal TMPs
Recognised by the Mu subunit of the AP1/2
