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 Uglade Lecture 11 > Flashcards

Professor Uglade Lecture 11 Flashcards

1
Q

What are the 3 forms of vesicular transport?

A

COPII vesicles
-COP1 vesicles
-Clathrin-coated vesicles

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

what happens to CFTR (cystic fibrosis transmembrane regulator) in cystic fibrosis?
WHat does CFTR help in?

A

-chloride channel that maintains hydration in lung airways
-mutation causes loss of CFTR function and Cystic fibrosis
-helps in ER translocation, chaperone assisted folding, ERAD (ER associated degradation)

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

What is the composition of CFTR (amino acids/helices)?
2. what type of protein is CFTR?

A

-has 1480 amino acids, 12 TM helices, and 2 cytoslic nucleotide binding domains (NBD)
-type 2 protein since it has a cytsolic N-terminus and loops

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

In translocation in CFTR was acts as the signal anchors?
-what determines the orientation in the membrane?
-what happens to other TM helices and N-linked glycan?

A

-TM1 and TM7 acts as signal anchors
-charges around TM1 and TM7 determine orientation in membrane
-other Tm helices are threaded in and out
-N-linked glycans attached during translocation

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

What is the most common mutation in CFTR?
What does the mutation disrupt/cause?

A

-most commoon mutation is deletion of Phe in NBD1 (F508)
-mutation disrupts hydrophobic core of NBD1 and therefore its folding
-mutant NBD1 cannot interact correctly with TM helices or NBD2

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

Where is mutatn CFTR degraded?

A

-retained in the ER and degraded, instead of trafficking to the plasma membrane

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

What does normal CFTR require to complete folding?
-In what complex do they transfer from cochaperons?

A

-CFTR requires cytsolic chaperones like DNAJ and HSP70 to complete folding
-transfer from HSP70 to HSP90 via complex by TPR co-chaperone HOP
-HSP90 co chaperones also help folding

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

WHy does CFTR go through calnexin cycle?

A

-because of the N-linked glycan

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

How is mutant CFTR selected for ERAD, what does it do?

A

-by the E3 ligases, which is a complex in the ER membrane that moves the protein out of membrane and passes through p97 protein where it is Ub and degraded by proteasome

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

Where are HSP70-CHIP complex and TM E3 ligase in CFTR ERAD process?>

A

-HSP70-CHIP in cytosol
-TM E3 ligase complexes in the er

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

What do specialized co chaperones do and what doews p97 do for CFTR?

A

-specialized co chaperone also promote ERAD
-p97 helps to extract mutant CFTR from membrane

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

How does COP-II transport vesicles, what direction?

A

-vesicles transport from ER to Golgi (anterograde-in the direction of flow)

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

How does Cop-I transport vesicles?

A

-vesicles transport from Golgi to ER (retrograde-in the opposite direction of flow)

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

How are CopII and COPI diff?

A

the coats have related mechanisms, but diff proteins involved

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

How does clathrin coated vesicles (CCV) transport vesicles?

A

-from golgi and PM to endosomes

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

What part of initation is common with all vesicle formation?

A

-some event on the membrane starts the process of forming a vesicle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

In the coat formation of vesicles what do the adaptors interact with/collect?
What is a coat?

A

-cytosolic adaptor proteins interact with initiator
-adaptors collect TM cargo, or cargo receptors
coat is the protein framework that is formed on top of adaptors to shape the vesile bud from the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is fission in vesicle formation?
what is uncoating?

A

-when bud is pinched off to separate the vesicle to be moved out of ER/membrane
-coat is removed to allow vesicle targeting and fusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is Ras GTPase?
What is Sar1 and Arf?

A

Ras: siganl transduction
-they are monomeric GTPase “switches”
-GTP-bound state provides binding site for various effectors
-Sar1 and Arf are for COP vesicle initiation

20
Q

What is Rab?
What does GAP (GTPase activiating proteins) do?
What do GEFs do (guanine exchange factors ?

A

-Rab=vesicle targeting, allows fusino of vesicle to target organelle
-GAP-stimulate GTP hydrolysis
-GEF- causes release of GDP and binding of GTP (so our protein is activated)

21
Q

Where do CopII vesicles form?
What happens to proteins with exit signals, and misfolded proteins?

A

COPII vesicles form at specific ER exit sites
-proteins with exit signals are collected (cargo receptors)
-misfolded proteins are kept away (calnexin)

22
Q

What do transmembrane GEFs so in COPII initiation?
what does Sar1-GTP do?

A

TM GEFs at exit site induces GTP binding by Sar1
-Sar1-GTP exposes amphipatic helix and partially inserts into membrane to initiate vesicle formation

23
Q

What do adaptor and coat proteins do in COPII coat formation?

A

-Adaptor proteins (Sec23 and Sec24) bind activated Sar1 and TM cargo proteins, or cargo receptors for lumenal proteins
-Coat proteins (Sec13 and Sec31) bind adaptors and shape the membrane into vesicle

24
Q

what happens to a completed coat in COPII coat formation?
What is the energy in this stage used for/from?

A

Completed coat pinches the vesicle off from membrane
-Energy for shaping and pinching off the vesicle is only from protein interactions, not from GTP hydrolysis

25
Q

What do coat proteins form in COPII?
Why does adaptor act as a GAP (Guanosine triphosphatase activating protein) in Cop II uncoating

A

coat proteins (Sec13/31) form cage like structures around vesicle
-adaptor (sec23/24) acts as a GAP that allows Sar1 to hydrolyze GTP

26
Q

What happens in CopII uncoating when Sar1 hydrolyzes GTP?
Why is uncoating necessary?

A

GTP hydrolysis still slow-acts as trimer
-Sar1-GDP releases from vesicle membrane
-adaptors separate from Sar1 and coat separates from adaptors
-uncoating is necessary for vesicle fusion at golgi

27
Q

What does bulk flow do in the ER exit?

A

-proteins in ER are transported to the Golgi an PM by default, even with no exit signals
-but many protrins are exported much more efficiently, while some others return to the ER

28
Q

Where do Tm proteins have exit signals, what are they recognized by?

A

-TM proteins have exit signal on cytosolic side
-di-phenylanine (FF) at C-terminus (cytosolic c terminus so type 1 TM protein)
-Asp-X-Glu (DxE) within a sequence
-recognized by Sec23/24 adaptor

29
Q

How are lumenal proteins recognized in ER exit?

A

-lumenal proteins are recognized by various cargo receptors, which are TM proteins with exit signals (FF) (receptor also has 2 phenylalanine)

30
Q

What methos is used for forward vs retrieval pathway?

A

-forward CopII bc it is anterograde
-retrieval pathqay is COPI bc it is retrograde

31
Q

How are ER resident proteins transported to golgi and how are they returned?

A

transported to golgi by bulk flow
-they have signals that return them to ER

32
Q

What are the lumenal proteins in ER retrieval?

A

-KDEL-COO- at C-terminus
-recognized by transmembrane KDEL receptor, which itself has a KKxx motif at the cytosolic C-terminus (2 lysins and 2 other amino acids at c-terminus)

33
Q

What are the TM proteins in ER retrieval?
How are motifs recognized?

A

-KKxx-COO- at the cytosolic C-terminus (if protein is type I it will have this)
-NH3+-MxxRR at the cytsolic N-terminus (if type II will have this)
-motifs are recognized by COP-1 coat adaptors

34
Q

What/where does Arf1-GTP insert in COP1 coated vesicles?

A

-Arf1-GTP initiator inserts amphipathic helix into membrane (anchors arf-1 to membrane)

35
Q

what do adaptors collect in Cop1 coated vesicles, what does the coat do?
What are the adaptors for Arf1?

A

-there are 4 adaptors subunits that collect cargo
-Cop-1 coat (alphs, beta subunits) assembles on adaptors, shape and pinch off vesicle from membrane
-adaptors for arf-1 are GAPs, which dissociate the coat

36
Q

Where are PI-phosphates (phosphatadyl inositol) initiating vesicle formation?
What are PI on cytoslic face of membranes phosphorylated by?

A

PI-phosphates in PM and golgi to initiate vesicle formation
-phosphorlyated at different hydroxyl position by PI kinases

37
Q

What do PI-phosphates provide binding sites for?
What are other phosphor. states used for?

A

PI phosphates provide binding sites for diff proteins:
-PI(4,5)P2 (phosphorlyated in position 4+5): PM clathrin adaptors, dynamin
-PI (4)P: golgi clathrin adaptors
-other phosphor states are used for signal transduction

38
Q

What are some clathrin coated vesicle adaptors (CCV)?
What are the signals for cargo selection?

A

-adaptor proteins (AP-1, AP-2, others) bind to PI-phosphates and cargo in membrane
-signals include- monoUb, phsophorylation (signals to bring adaptors)

39
Q

What assists some adaptors in CCV?
What binds adaptors?

A

-arf GTPase assists some adaptors, but does not initiate CCV
-clathrin coat binds adaptors

40
Q

What is a clathrin cage composed of?

A

-calthrin triskelions (oligomers, 3 heavy and 3 light chains)

41
Q

Where do clathrin cages assemble?
What happens when clathrin forms a cage around a vesicle, how does it differ from COP1 and COPII?

A

-assemble on adaptors to shape the membrane, and form “coated pits”
-clathrin cage cannot pinch the vesicle off itself-needs dynamin
-it is divergent from COP-1 and COP-II, larger vesicle

42
Q

What pinches off clathrin coated vesicles?
How do the monomers of this assemble?

A

dynamin GTPase pinches off CCVs (not a member of Ras family)
-dynamin monomers assemble in GTP-bound state into oligomeric rings at the base of bud

43
Q

What does GTP hydrolysis cause in CCV fusion?
What do dynamin rings dissasemble into?

A

-GTP hydrolysis causes a coordinated constriction of ring that pinches off the vesicle (fission)
-dynamin rings dissasemble in GDP-bound state

44
Q

what weakens clathrin adaptor binding?
What is auxilin, where does it bind?

A

-PI-phosphatases modify PI (4,5)P2 to weaken adaptor binding
-Auxilin-DNAJ with clathrin-binding domain and J domain
-binds to assemebled clathrin cage, activtaes HSC70

45
Q

what does HSC70 bind to in clathrin uncoating?
what happens to released clathrin?

A

-HSC70 binds clathrin and induces a conformational change, that dissasembles coat into triskelions (cant form cage/vesicle)
-clathrin is released from HSC70 and recycles to membrane

ANAT 212 pre midterm (9 decks)

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