BIO230H1 Chapter Notes - Chapter 7: Ubiquitin Ligase, Eif2, Eif2B

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Note: the phosphorylation of a protein by kinase can either increase or decrease the protein"s activity, depending on the site of phosphorylation and the structure of protein. Proteins that bind and hydrolyze gtp are ubiquitous cell regulators. Gtp-binding protein aka gtp ase: when bind to gtp conformational change. Regulatory proteins gap and gef control the activity of gtp- binding protein by determining whether the gtp or gdp is bound. Gtpase activating protein; inactivate ras by binding and hydrolyzing. Guanine nucleotide exchange factor: binds to gdp-ras and cause ras to release. Proteins can be regulated by the covalent addition of other proteins. Ubiquitin: can covalently attach to target protein. Major form produce poly ubiquitin lys48 linked ubiquitin attaching to the lysine sidechain. Other : sumo (small ubiquitin related modifier ) An elaborate ubiquitin- conjugating system is used to mark proteins. C-term of ubiquitin activated by ubiquitin-activating enzyme (e1) Ubiquitin-conjugating enzyme (e2) act with ubiquitin ligase (e3)

Related Questions

Question 22

What intrinsic enzymatic activity do G proteins have?

They are ATPases

They are glycosidases

They are GTP synthases

They are GTPases

Question 23

How are G proteins activated?

The GTP dissociates from the G protein and GDP associates with the G protein

The GDP dissociates from the G protein and GTP associates with the G protein

The G protein synthesizes GTP from GDP

The G protein synthesizes GTP from ATP

Question 24

How are G proteins inactivated?

Hydrolyze ATP

Bind GTP

Bind ATP

Hydrolyze GTP

Question 25

What is a GTPase activating protein (GAP)?

It hydrolyzes GTP

It promotes release of GDP and binding of GTP of a G protein

It speeds up the rate of GTPase activty of a G protein

Question 26

What is a guanine nucleotide exchange factor (GEF)?

It speeds up the rate of GTPase activty of a G protein

It hydrolyzes GTP

It promotes release of GDP and binding of GTP to a G protein

Question 27

Which of the following types of enzyme activate G proteins?

GAP

GEF

Question 28

Which of the following types of enzyme inactivate G-proteins?

GAP

GEF

Question 29

What is receptor internalization and recycling?

It is when the receptor is co-translationally imported into the ER before being degraded by the unfolded protein response

It is when the receptor is endocytosed and then the vesicle fuses with the endosome, releases ligand and the receptor is returned to the plasma membrane

It is when the receptor is digested with proteases into amino acids and those amino acids are used to synthesize a new receptor

It is when the receptor cycles in and out of the nucleus

Question 30

How do large proteins get into the nucleus?

Simple diffusion

Facilitated diffusion through the nuclear pore

Active transport through the nuclear pore

Question 31

How easy is it for the following reaction to occur?

ADP + Pi â ATP

This is very exergonic and highly favorable

This is very endergonic and highly unfavorable

This is slightly exergonic and somewhat favorable

Question 32

The hydrolysis of ATP is highly...

Exergonic

Endergonic

Choose only one correct answer

QUESTION 1

Transautophosphorylation occurs in which two of the followingsignaling pathways?

a.GPCR and RTK pathways

b.RTK and Integrin/FAK pathways

c.S/TKR and PKA pathways

d.GPCR and Ras pathways

e.MAPK and cAMP pathways

QUESTION 2

Which of the following receptors are activated by GTP?

a.G protein coupled receptors only

b.tyrosine kinase receptors only

c.both G protein coupled receptors and tyrosine kinasereceptors

d.neither G protein coupled receptors nor tyrosine kinasereceptors

QUESTION 3

Why can both GPCR and RTK pathways activate calmodulin?

a.Because both activate PLC

b.Because both activate PI3K

c.Because both trigger an action potential

d.Because both activate Ras

e.Because both activate PKA

QUESTION 4

Ion channel receptors __________ enzymes. They __________ bindsignaling ligands.

a.are, do

b.are not, do

c.are, do not

d.are not, do not

QUESTION 5

PIP2 is cleaved by ___________ to produce _____________.

a.phosphodiesterase, DAG and IP3

b. phospholipase C, DAG and IP3

c. phosphodiesterase, DAG and calcium

d. phospholipase C, DAG and calcium

QUESTION 6

Why are integrins considered to be signaling proteins?

a.Because they bind ECM

b.Because they bind heterotrimeric G proteins

c.Because they bind FAK

d.Because they bind MAPK

e.Because they bind Sos

QUESTION 7

Why isnât tubulin considered a G protein?

a.Because it doesnât propagate a signal in a signalingpathway

b.Because it doesnât bind to GPCR

c.Because it doesnât bind to a GEF or a GAP

d.Because it doesnât undergo transautophosphorylation

e.Because it doesnât bind GTP

orangebutterfly756

1/ G-proteins are a commonly found in cell signaling pathways, which of the following events normally activates a GTP-binding protein?

(a) GTP hydrolysis by the protein

(b)Activation of an upstream GTPase-activating protein

(c)Exchange GDP for GTP by the activation of an upstream guanine nucleotide exchange factor(GEF)

(d)Pi release after GTP hydrolysis

2/ Which of the following inactivates a G-protein?

(a) The Î² subunit exchanges its bound GDP for GTP.

(b) The GDT bound to the Î± subunit is hydrolyzed and forms GDP

(c)The Î± subunit exchanges its bound GDP for GTP.

(d) TheÎ²Î³ complex inactivates the G-protein

3/ Olfactory receptors where first hypothesized to be numerous receptor types that were able to recognize specific odorants. We now know that olfactory receptors are made up of ONE receptor family, which is one of the largest gene families know in the human genome. Which of the receptors below comprise the olfactory receptor family?

(a)RTK

(b) Delta-Notch

(d) Ion Channel Receptors

4/ Which of the following are possible responses a cell may have as a result of activation of a cell signaling pathway?

(a) Change in gene expression

(b) Alteration of activity of metabolic enzymes

(d) All of these

5/ Which of the following statements about the cytoskeleton is false?

(a) The cytoskeleton is made up of three types of protein filaments.

(b) The cytoskeleton controls the location of organelles in eukaryotic cells.

(d) The cytoskeleton of a cell can change in response to the environment.

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BIO230H1 Chapter Notes - Chapter 7: Ubiquitin Ligase, Eif2, Eif2B

BIO230H1 Full Course Notes

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