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ANAT 365 - Cellular Trafficking > Regulation of Receptor Transport (GPCRS) > Flashcards

Regulation of Receptor Transport (GPCRS) Flashcards

1
Q

How many transmembrane domain receptors are found in GPCRs?

A

Seven

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2
Q

____________ loops are for DNA binding sites and __________ loops are sites of regulation

A

Extracellular; intracellular

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3
Q

What are some of the stimuli that activate GPCRs?

A

Light, odors, endogenous small molecules, proteins, Ca++

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4
Q

What are the main events of GPCRs?

A

Desensitization, internalization, recycling

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5
Q

Where are GPCRs assembled?

A

In the ER

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6
Q

Which of the following are cell surface receptor trafficking pathways?
i. Transport to the Golgi for processing
ii. Transport from the plasma membrane by endocytosis to the early endosome
iii. Targeted via TGN to the plasma membrane
iv. Sorted from endosomes to lysosomes for degradation

A

All of the above

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7
Q

Secretory vesicles arise from the ________ face of the Golgi

A

Trans

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8
Q

Do all ways from the TGN lead to the cell surface?

A

No, some lead to early endosomes

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9
Q

What roles do RAMPs play in GPCR regulation?

A

Chaperones, pharmacology switch, signaling switch, trafficking switch

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10
Q

Which receptor interacts with RAMP3 and is rapidly recycled?

A

AM2

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11
Q

Which receptor interacts with RAMP2 and is degraded?

A

AM1

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12
Q

How is the GABAB receptor able to reach the plasma membrane?

A

GABAB1 and GABAB2 subunits inactivate ER retention signal in C-terminus of GABAB1 and transport to the PM from the ER

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13
Q

Unassembled GABAB1 subunits leave the ER to enter the ______________ where they are recognized by COPI

A

Cis-Golgi

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14
Q

In both COS-7 and AtT20 cells, sst2A is located at the ______________ while sst5 is located ___________________

A

Cell surface; intracellularly

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15
Q

Following somatostatin stimulation, where are sst5 receptors located?

A

At the cell surface

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16
Q

What causes the redistribution of sst5 receptors to the cell surface following somatostatin stimulation?

A

Sst5 internalization upon binding of SOM creates a signal for rapid recruitment of spare intracellular sst5 receptors to the cell surface

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17
Q

Place the steps of GPCR desensitization in order
i. H binds to GPCR and alpha subunit is released
ii. PKA phosphorylates GRK2
iii. GRK2 goes to PM and phosphorylates C-terminus of G-coupled proteins
iv. Arrestin binds to phosphorylated sites and causes desensitization
v. cAMP regulated by alpha subunit

A

iii. i, v, ii, iv

18
Q

Homologous desensitization uses ____________

A

GRKs

19
Q

Where are the following GRKs located?
i. GRK5 and GRK7
ii. GRK1, GRK4 and GRK6
iii. GRK2 and GRK3

A

i. Cytosol at rest and PM when activated
ii. Membrane
iii. Controlled by G-beta-gamma and PIP2

20
Q

Which of the following do GRKs interact with?
i. PI3K
ii. Clathrin
iii. Tubulin, actin
iv. Myosin

A

i, ii, iii

21
Q

Heterologous desensitization uses which molecules?

A

Second messenger kinases

22
Q

Which second messenger kinase phosphorylates the C-terminus of G-coupled proteins?

A

PKA or PKC

23
Q

How are heterologous and homolgous desensitization different?

A

Different phosphorylation sites

24
Q

What are the key adaptor proteins in GPCR desensitization and internalization?

A

Arrestins

25
Q

Arrestin 1 and 4 are specific to the ____________, while arrestin 2 and 3 are found in ______________ receptors

A

Eyes; beta-2-adrenergic

25
Q

Which domains in arrestins are for second messenger kinases and affinity for clathrin and AP2?

A

C domain for clathrin and AP2
N domain for second messenger kinases

26
Q

When stimulated, arrestins in the ______________ translocate to the _____________

A

Cytoplasm; PM

27
Q

What is the role of beta-arrestin in beta-2-adrenergic receptor signal?

A

It promotes desensitization and targets cAMP-inactivating PDE enzymes to the activated receptor

28
Q

What is the use of arrestin in GPCR endocytosis?

A

Targeting clathrin coated pits and helps fusion of the vesicle to form the endosome

29
Q

In response to SOM, sst2A is ________________ and targeted to clatherin-coated pits

A

Desensitized

30
Q

The localization of sst2A and syntaxin-6 is insensitive to the TGN-dispersing drug ___________

A

Brefeldin A

31
Q

Internalized sst2A receptors reside in a syntaxin-6 ___________ compartment which is distinct from the TGN and the recycling endosome

A

Positive

32
Q

True or false: The sequestrating compartments of sst2A are similar to Glut4 storage vesicles

A

True

33
Q

The hypothesis to the homologies of GSVs and sequestrating compartments of sst2A is that GSV-like carriers are recycles in response to ____________ signaling

A

Hormonal

34
Q

Overexpression of beta-arrestin1-VH3D has what effect on beta-2-adrenergic internalization?

A

It decreases

35
Q

What are the two classes of GPCRs?

A

Class A and class B

36
Q

Associate the following descriptions to the class of GPCRs
i. Long interaction with beta-arrestin, co-localization in endosomes, high affinity for visual arrestin
ii. Short interaction with beta-arrestin, no colocalization in endosomes, low affinity for visual arrestin

A

i. Class B
ii. Class A

37
Q

Which of the following are class A or B receptors?
i. Dopamine D1
ii. Neurotensin NTR1
iii. Vaspressine V2

A

i. Class A
ii. Class B
iii. Class B

38
Q

Chimeras between what receptors inverse the internalization properties of the receptors?

A

Beta-2-adrenergic and vasopressin V2R

39
Q

Slow dephosphorylation is associated with which class of receptor?

A

B

40
Q

Rapid recycling and dephosphorylation are linked to which class of GPCR?

A

A

41
Q

Ubiquitination of beta-arrestin signals for _______________ of the receptors

A

Degradation

ANAT 365 - Cellular Trafficking (5 decks)

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