Signaling #7

Question 1

What are GPCRs linked to?

Answer 1

Gq, Phospholipase C (PLC) signaling and PIP2 signaling pathways

Question 2

What does PKC stand for?

Answer 2

Protein Kinase C

Question 3

How is PKC activated?

Answer 3

By different domains of PKC being regulated

Question 4

What regulates ER localized IP3 receptor activity?

Answer 4

Calmodulin

Question 5

What does calmodulin decode?

Answer 5

Transient rises in [Ca++]

Question 6

What is the link between NO and calmodulin mediated signaling?

Answer 6

NO activates guanylate cyclase, increasing cGMP which activates PKG, influencing calcium signaling

Question 7

What is Tubby’s role in signaling?

Answer 7

Tubby is a transcription factor released by activation of phospholipase C

Question 8

What happens when PIP2 is broken down?

Answer 8

It leads to the release of Tubby, allowing it to regulate gene expression

Question 9

What is the effect of Tubby mutations in mice?

Answer 9

Mice develop adult onset obesity

Question 10

What domains does the Tubby protein have?

Answer 10

DNA binding domain and gene transcription activation domain

Question 11

What does PIP2 facilitate in channel activity?

Answer 11

Rapid modulation of channel activity by localized changes in PIP2 synthesis or breakdown

Question 12

What is the role of TRPV1 channels?

Answer 12

They are non-selective cation channels that respond to pain-related stimuli

Question 13

What enhances TRPV1 sensitivity?

Answer 13

Diverse hydrophobic ligands, e.g., capsaicins from peppers

Question 14

What does Bradykinin do in inflammation?

Answer 14

It activates GPCRs that increase TRPV1 channel activity

Question 15

What is the effect of Ca++ on calmodulin?

Answer 15

Ca++ binds to calmodulin, partially activating it

Question 16

What is the role of phosphorylase kinase?

Answer 16

It hydrolyzes glycogen to glucose 1-phosphate

Question 17

What activates phosphorylase kinase?

Answer 17

Both Ca++ and cAMP

Question 18

What initiates muscle contraction?

Answer 18

The release of acetylcholine (ACh) at the neuromuscular junction

Question 19

How many nicotinic acetylcholine receptors are present in muscle?

Answer 19

About 20 million

Question 20

What is the result of ACh binding to nAChRs?

Answer 20

Allows ~50,000 cations into the muscle cell, causing depolarization

Question 21

What does the voltage change in muscle cells lead to?

Answer 21

An action potential that spreads over the muscle membrane

Question 22

What channels interact directly with the ryanodine receptor?

Answer 22

CaV1.1 voltage-operated Ca2+ channels

Question 23

Where does Ca2+ release occur in muscle cells?

Answer 23

At the triadic junction between the SR and T-tubule

Question 24

Fill in the blank: The breakdown of PIP2 is linked to the activation of _______.

Answer 24

Tubby the transcription factor

Question 25

True or False: TRPV1 channels are sensitive to both heat and protons.

Answer 25

True

Question 26

What type of receptor is RYR1?

Answer 26

The ryanodine receptor (RYR1) ## Footnote RYR1 is crucial for calcium release in muscle contraction.

Question 27

Where does the coupling between depolarization and Ca2+ release occur?

Answer 27

At the triadic junction ## Footnote This is where the sarcoplasmic reticulum (SR) contacts the T-tubule.

Question 28

What connects the SR and T-tubule membranes?

Answer 28

Aggregates of CaV1.1 L-type channels and RYR1 ## Footnote These aggregates facilitate the transmission of information across the gap.

Question 29

What triggers the RYR1 to release Ca2+ from the SR?

Answer 29

Voltage-dependent conformational change of CaV1.1 L-type channel ## Footnote This change occurs in response to depolarization.

Question 30

What role does Ca2+ play in muscle contraction?

Answer 30

It acts on troponinC to trigger the interaction between actin and myosin ## Footnote This is essential for muscle contraction.

Question 31

How is muscle relaxation achieved?

Answer 31

By pumping Ca2+ back into the SR by SERCA1 ## Footnote SERCA1 stands for sarco/endo-plasmic reticulum Ca2+ ATPase 1.

Question 32

What is the source of energy for muscle contraction?

Answer 32

Glucose stored as glycogen ## Footnote Glycogen is hydrolyzed to glucose for energy.

Question 33

What enzyme converts inactive phosphorylase b into active phosphorylase a?

Answer 33

Phosphorylase Kinase ## Footnote This conversion is crucial for energy supply regulation.

Question 34

What initiates the control of energy production by adrenaline?

Answer 34

Activation of the cAMP signaling pathway ## Footnote This pathway is critical in the response to adrenaline.

Question 35

What receptor does adrenaline bind to?

Answer 35

β-adrenergic receptor ## Footnote This receptor activates the Gs protein.

Question 36

What does adenylyl cyclase produce in response to adrenaline?

Answer 36

Cyclic AMP (cAMP) ## Footnote cAMP acts as a second messenger in signaling pathways.

Question 37

What is the role of protein kinase A (PKA) in energy metabolism?

Answer 37

It phosphorylates phosphorylase kinase ## Footnote This activation converts phosphorylase b to phosphorylase a.

Question 38

True or False: Phosphorylase kinase is sensitive to Ca2+.

Answer 38

True ## Footnote This sensitivity provides feedback for energy metabolism and contraction.

Question 39

Fill in the blank: Phosphorylase a hydrolyses glycogen to _______.

Answer 39

glucose ## Footnote Glucose enters glycolysis to generate ATP for contraction.