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Cell Biology > Lecture 18 study guide > Flashcards

Lecture 18 study guide Flashcards

1
Q

What is the largest family of cell receptors?

A
  1. GCPRs
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2
Q

GCPR characteristics

A
  • 7 transmembrane domains and binds to a GTPase
  • When activated, binds to a gamma, alpha, and beta subunit that have different downstream effectors
  • Acts as a GEF
  • Subfamilies include Rhodopsin
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3
Q

RTK

A
  • Dimerizes
  • Phosphorylates itself in order to recruit signaling proteins to relay targets downstream
  • Subfamilies include insulin receptors
  • Largest class is Eph receptors
  • Uses an adaptor protein to bind to Ras-GEF
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4
Q

Notch

A
  • Attaches to a ligand presented on the surface of another cell
  • Cleaved tail acts as a transcription factor
  • Requires direct cell to cell contact
  • Functions in development of multicellular organisms
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5
Q

The alpha subunit of a g-protein acts as a?

A

GTPase

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6
Q

G protein effectors act as a?

A

GAP

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7
Q

True or False: G proteins and their effectors are attached to the lipid membrane (lipid linked)?

A

True

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8
Q

True or False: the alpha subunit of the G protein is bound to GTP upon association with a GCPR.

A

False

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9
Q

What is the function of adenylyl cyclase?

A

increase of cAMP levels by breaking down ATP

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10
Q

What is the role of GCPR in regulating adenylyl cyclase?

A

can regulate or inhibit adenylyl cyclase activity depending on the signaling molecules

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11
Q

What protein complex associated with GCPRs activate potassium channels?

A

G beta-gamma complex

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12
Q

Where are the following Ptdlns found in the cell?
a. PI-3P
b. PI-4P
c. PI-4,5P
d. PI-3,5P

A

a. endosomes
b. golgi
c. plasma membrane
d. lysosomes

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13
Q

What are the two parts of a Ptdlns?

A

Diacylglycerol (a double lipid tail) and an inositol (sugar) head.

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14
Q

What do the numbers in question 10 stand for? (What does the 3 and 5 in PI-3,5 mean?)

A

Which OH (position) is phosphorylated.

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15
Q

What is the function of PI-3P

A

Recruits endosomal proteins such as ESCRT proteins and participates in endosomal trafficking.

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16
Q

What is the main purpose of Ptdins binding domains? (besides binding to Ptdins)

A

Localize protein to the specific membrane. FYVE domain is an example of a Ptdln binding domain which localizes a protein to that membrane.

17
Q

What protein activates PIs by breaking them into their two parts?

A

Phospholipase C

18
Q

Which two molecules must bind to PKC to activate it?

A

Diacylglycerol and Ca2+

19
Q

Ca2+ functions as what in cell signaling?

A

Second Messenger

20
Q

What protein recognizes a rise in Ca2+ levels and activates downstream targets? Give an example of these targets that are involved in memory formation?

A

Calmodulin, CaM-Kinases (Calmodulin dependent kinases)

21
Q

True or False: intramolecular Ca2+ levels are very high.

A

False: they are very low. This keeps the cell sensitive to any change in calcium levels which allows it to be a ubiquitous second messenger.

22
Q

What kind of protein is rhodopsin

A

A light sensitive GCPR

23
Q

PDE acts to keep cytosolic cGMP levels high or low?

A

Low. It converts cGMP to GMP

24
Q

Open Na+/Ca2+ ion channels require high or low levels of cGMP?

25
Q

Retinal is the cofactor found in rhodopsin. In active rhodopsin is retinal trans or cis?

26
Q

What is the role of phosphorylation of rhodopsin?

A

Phosphorylation of rhodopsin works to decrease its activity. This allows our cells to adapt to changes in light levels.

27
Q

What happens to rhodopsin in the presence of very high light?

A

Arrestin binds inactivating rhodopsin

28
Q

What is the role of Eph Receptors?

A

Regulates cell adhesion and migration

29
Q

A RTK is found that contains a fibronectin-like domain. What subfamily is this receptor likely from?

A

Eph receptors

30
Q

A RTK is found that contains a cysteine rich domain and three intramolecular disulfide bridges. What subfamily is this receptor likely from?

A

EGF receptors

31
Q

What is the role of EGF? Where are the receptors for this signal located?

A

a potent promoter of cell survival, growth and proliferation - almost all human cells respond to EGF (they express the EGF receptor)

32
Q

How are RTKs phosphorylated?

A

They dimerize and phosphorylate each other

33
Q

What protein involved in the RTK signaling pathway activates MAP kinase scaffold proteins?

A

Ras GTPase

34
Q

What are the two main consequences of the MAP kinase pathway?

A
  1. Changes in protein activity and
  2. gene expression
35
Q

In the MAP kinase pathway, which protein is specifically activated first?

A

MAP Kinase Kinase Kinase

Cell Biology (18 decks)

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