Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ANAT 212 pre midterm > Professor Ugalde Lecture 13 > Flashcards

Professor Ugalde Lecture 13 Flashcards

1
Q

What is the difference between proteins used when going to endosome vs going to lysosome for tethering?

A

-to endosome–>Rab5 and CORVET
-to lysosome–>Rab7 and HOPS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

For lysosome and endosome tethering what is the difference/similarity in complex+subunits?

A

-complexes have the same core subunit
-different end subunits bind different Rabs
-Also bind SNARES

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How does clustering of tethers occur, what protein/activities are involved?

A

-Rab5 effectors have GEF or PI kinase activity on early endosome
-GEF activity produces more Rab5-GTP in local area of membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What do PI-phosphatases do in clustering of tethers?
what do the cluster of tethers form?

A

-PI-phosphatases provide additional binding sites for vesicle tethers
-cluster of tethers form “landing site” for vesicle (does not involve membrane thickness or lipid content)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the importance of the increase of GEF in clustering of tethers?

A

more GEF–> more Rab5, allowing more production of PI, and more tethers being formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

In endocytosis pathway where do vesicles traffic?
-What does early endosome matuer into, what does membrane switch from?

A

-vesicles traffic between PM, early endosome and trans-golgi
-early endosome matures into multivesicular body (MVB) an late endosome
-membrane switches from Rab5 to Rab7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is endocystosis?
what does a late endosome mature into in endocytosis pathway?

A

-taking cargo from exterior of cell into cell membrane
-late endosome matures into lysosome
-other vesicles traffic to lysosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does Rab5 activate?
what does Rab5 effector do?
What does Rab7 effector do

A

-Rab5 at endosomes activates Rab7
-Rab5 effector and tether (CORVET) is GEF for Rab7
-Rab7 effector is GAP to inactivate Rab5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens when Rab5 vesicles fuse with early endosomes?

A

-more and more Rab7 is activated and less and less Rab5 stays actiave, membrane becomes late endosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a SNARE, what recruits them?

A

SNARE proteins: family of membrane proteins that carry out vesicle fusion
-Rabs and tethers can recruit SNAREs to fusion site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What can v-SNARES recognize, how does the complex form, how is specificity determine?

A

-v-SNAREs on vesicles recognize partner t-SNAREs on target membranes
-complexes form after tethering
-unique combination of v and t-SNARES determine targeting specificity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the difference between v and t SNARES?
What do v and t SNares form?

A

-v-snares: are monomers with single TM helical domain
-t-SNAREs: are trimers with combination of TM and peripheral subunits
-correct set of v and t Snares form a stable tetramer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What do SNARE complex induce?

A

-multiple SNARE complexes form at a target site to induce vesicle fusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why is a v and t-SNARE complex very stable?
How are they folded?

A

-it has a 4 helix bundle
-the folding process pulls the membranes close together, generating physical strain like a spring and it is not dependent on ATP or GTP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What do SNARE complexes form a ring around?
How does the bending of SNARE TM contribute to structure?
What happens to outer+inner layers of membrane, what does this do?

A

-SNARE forms a ring around the vesicle contact site
-SNARE TM anchors are bent and strained, exerting a force that holds the membrane together
-outer+inner layer of membranes fuse, relieving strain in the SNARE complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens to SNARE after fusion?
What dissociates v and t-SNAREs

A

after fusion, the SNARE complex is stable, unstrained and inactive
-an AAA-family ATPase (NSF) dissociates the SNAREs which is essential for continution of vesicle traffic

17
Q

What happens to v and t SNARES after dissociation?

A

-t-SNAREs become active again (stay in compartment where they belong to bring more vesicle)
-v-SNAREs are recycled back to their dono membrane by vesicles

18
Q

What happens in homotypic fusion, what is fused?
when does ER and golgi reform?

A

-donor and target membranes are the same
-the fusion of COP-II vesicles into vesicular-tubular cluster that becomes cis-golgi
-re-formation of ER and golgi after cell division

19
Q

What type of v and t snares are in homotypic fusion?
What separates the SNAREs and why?

A

-both membranes have identical v-and t-snares already in complexes and inactive
-SNAREs must be separated by NSF to allow new fusion

20
Q

What does NSF bind?
What happens to NSF during ATP-hydrolysis?

A

NSF binds SNARE complex through adaptor protein (alpha SNAP)
-NSF twists and pulls during ATP hydrolysis

21
Q

What is needed to unwind the SNARE helices?

A

-multiple cycles of ATPase unwind the SNARE helices

22
Q

What do CCV (clathin coated vesicles) mediates in endocytosis?
-Where are some PM proteins transported?

A

-CCVs mediate endocytosis from PM to early endsome
-Some PM proteins are transported to recycling endosome, for exocytosis back to PM (once cargo is in we need to recycle receptors)

23
Q

Where are lysosomal proteins trafficked from and where?
What does endosome invaginate to form?

A

-trafficked from trans-golgi to endosomes, their receptors are trafficked back
-invaginates to form multivesicular body (MVB) and late endosome

24
Q

What does late endosome turn into and what for?

A

-late endosome matures into lysosome, for degradation of proteins and lipids

25
Q

What are extracellular ligands bound by and transported to for receptor recycling?

A

-extracellular ligands are bound by Transmembrane PM receptors, transported to early endosome for sorting

26
Q

What does the lower than normal pH in endosome cause?

A

-lower pH than extracellular space in endosome causes ligands to separate from receptors
-causing a change in average charge on proteins, interactions are weakened

27
Q

Where are empty receptors recycled back to?
Where do free ligands progress to?

A

-empty receptors are recycled back to PM
-free ligands progress to lysosome

28
Q

What is retrograde traffic?
Where do extracellular receptors go
-Where are receptors that bring proteins to golgi returned?

A

-traffic of proteins from endosomes to PM or trans-golgi
-extracellular receptors to PM
-receptors that bring proteins to the lysosome are returned to golgi

29
Q

what type of vesicles are involved with retrograde traffic?
what does it require?

A

involves membrane tubules or tubular vesicle, not round coated vesicles (ex. not COPI, COPII, and CCV since they are coated)
-requires the retromer protein complex

30
Q

What initiates retromer formation?
What binds Rab and selects TM cargo proteins?

A

-RAb5-GTP or Rab7-GTP initiates the formation
-Cargo adaptor (Vps26/29/35) binds Rab and selects TM cargo proteins

31
Q

In retromers what binds PI(3)P, what are the other versions used for?
What causes membrane to curve?

A

Sorting nexin SNX complex binds adaptor and PI(3)P
-different SNX proteins for Golgi or PM traffic
-causes membrane to curve by interacting with lipids, not by forming a rigid coat

32
Q

What do SNX and adaptor form?

A

SNX And adaptor form complete retromer unit

33
Q

What do clusters of retromers form?
What do dynamin and cytoskeleton do?
What does GTP-hydrolysis by Rab cause, why is it necessary?

A

-clusters of retromer shape the membrane into long tube, it does not form a rigid cage
-dynamin homologs and cytoskeleton motor proteins pinch off the membrane
-GTP hydrolysis by Rab causes dissociation of retromer complex and uncoating (necessary for fusion with target)

34
Q

How are some TM proteins marked for endocytosis?
-how is it recognized?
-What happens when UB is removed vs when its not?

A

-they are marked by modification with mono-UB at PM
-recognition by CCV adaptors
-if UB removed, proteins are recycled by PM, if Ub not removed it is a signal for lysosomal degradation

35
Q

How does early endosome mature?
What happens to MVB contents?

A

-Early endosome matures into MVBs by invaginating and pinching off membrane
-MVB contents cant ve recycled to PM anymore

36
Q

What is MVB invagination?

A

-a series of ESCRT protein complexes shape and pinch off vesicles into the lumen of an endosome

37
Q

What does ESCRT-0 bind in MVB formation?
What do ESCRT1 and II form?
What does ESCRTIII form?

A

-binds PI(3)P and collects mono-ub cargo proteins, provides binding site for ESCRT-1
-ESCRTI and II form the neck of the bud
-ESCRTIII forms oligomers to pinch off the bud to form vesicle

ANAT 212 pre midterm (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions