IP3-calcium-PKC Pathways

Question 1

What else can second messengers be made from

What can act as a second messenger

Answer 1

Lipids

Calcium

Question 2

What is a phosphoglyceride made of

Answer 2

Polar head group (with a phosphate)

Glycerol backbone

Fatty acid chain

Question 3

What are lipids that have phosphate groups

Answer 3

Phospholipids

Question 4

Fatty acyl chains are _____

Answer 4

Hydrophobic

Question 5

Give example of a phosphoglyceride

Answer 5

Phosphotidyl inositol

Question 6

What is a PH domain

Answer 6

A domain of phospholipase c

Called pleckstrin homology domain

Question 7

What does the PH domain of phospholipase c bind to

Answer 7

Bind to the lipid phosphoinositide which is in the plasma membrane

It binds to the phosphorylated inositol ring of the phosphoinositide

Question 8

How does smooth muscle (muscle around guts) contraction happen

Answer 8

It’s stimulated by the neurotransmitter acetylcholine

The acetylcholine binds to muscarinic cholinergic receptors to make tension for contraction

Tension increase as acetylcholine increases

Question 9

What can terminate contraction of smooth muscles

Answer 9

Epinephrine

Question 10

Describes how second messengers can be made by breaking down phosphoinositides (lipids)

Answer 10

A kinase phosphorylates the inositol ring of phosphoinositide 2 times (to make pi(4,5)p2 (3 phosphates)

Then once acetyl choline bind to GPCR, the alpha on the GPCR interacts with PIPLC (phospholipase c bound to PI)

PIPLC is the effector which cuts the pi(4,5)p2 phospholipid in the membrane

This release the PI (phosphoinositide) ring (ip3) which goes in the ligand gated IP3 receptor to release calcium

If calcium is released, contraction occurs

Question 11

What reaction does the effector PIPLCbeta catalyze

Answer 11

It helps cut pi(4,5)p2 into

IP3 (the ring)

And DAG

Both are second messengers

Question 12

What is DAG (diacylglycerol)

Answer 12

A plasma membrane lipid

second messenger

recruits and activates effector protiens with a DAG binding c1 domain

Ex. they recruit and activate protien kinase c

Question 13

What does protein kinase c help with

Answer 13

Cell growth and differentiation

Cell metabolism

Cell death

Immune responses

Muscle contraction

Question 14

What is IP3

Answer 14

Second messenger

Formed at the membrane then diffuses into the cytosol

Binds to the specific IP3 receptor at the smooth ER

Question 15

What is the ip3 receptor

Answer 15

A tetrameric gated calcium channel on the smooth er

Opens when IP3 binds and lets calcium ions diffuse into the cytoplasm

Question 16

Slide 13

Answer 16

Idk

Question 17

How can be see calcium levels in a living cell

Answer 17

By introducing fluorescent calcium binding compounds like Fura2

Fura2 is light emitting and calcium sensitive (red when calcium)

Check the diffusion of the fura2 across the membrane

The dye cant leave the cell once it’s entered

Question 18

What can the second messenger ca2+ do that cAMP can’t

Answer 18

Ca2+ can activate effectors through calcium binding protiens

Question 19

What is an example of a calcium binding protien

Answer 19

Calmodulin

It has 4 binding sites for calcium

Question 20

How does the activation of effectors happen using calmodulin

Answer 20

Is concentration of calcium increases, the ca ion bind to calmodulin

The confirmation of calmodulin changes and its affinity for effectors it increased

Question 21

Once calmodulin is bound with ca what can it do

Answer 21

It can then activate binding protiens like kinases,
phosphodiesterases,
ion channels or
calcium transport mechanisms

Question 22

What do phosphodiesterases do

Answer 22

Turn off cAMP dependent pathways

Question 23

Slide 17

Answer 23

Idk