Signals thru lipids and calcium Flashcards

1
Q

True or False

Phosphorylation can only be stimulatory (positive allosteric modulator

A

False

Phosphorylation can be stimulatory or Inhibitory

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2
Q

Looking at the Glycogen Breakdown and Synthesis regulation,

What are reactions are examples of

Phosphorylation is a positive allosteric modulatory?

Phosphorylation is a negative allosteric modulatory?

A

Look at image

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3
Q

True or False

Whether phosphorylation is stimulatory or inhibitory depends on the difference between different target proteins and/or the difference between different phosphorylation sisters on the same target proteins.

A

True

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4
Q

Where does epinephrine originate?

Where do its secrets from?

What are the major targets?

What type of G alpha subunit?

A

Epinephrine originates and secreted from the adrenal gland

The major target is the skeletal muscle via the beta-adrenergic receptor.

Gs

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5
Q

What is the glucogen target site?

What type of G alpha protein is used?

Where is glucagon secreted?

A

Target site: Glucagon receptor in the liver

G alpha protein: Gs

Secreted by the alpha cells of the pancreas

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6
Q

Where is insulin secreted?

What are the major target organs?

A

Insulin is secreted in the pancreas

Major targets are skeletal muscle, liver, and fat.

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7
Q

Insulin signaling inhibits breakdown and stimulates synthesis via _______________________, the key is the action of ________________, which exerts the opposite effects as PKA/phosphorylation kinase.

Pathways of regulating existing proteins to change activity

A

Protein phosphatase activation

protein phosphatase PP1

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8
Q

What is the cycle for stimulation of Breakdown and Inhibition of Synthesis?

A
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9
Q

Name the following of the structures

Where are these structures located?

Which one of these structures is cleaved by PI-PLC and creates diacylglycerol and IP3?

A
  1. phosphatidylinositol (PI)
  2. PI 4-phosphate [PI(4)P]
  3. PI 4,5-bisphosphate [PI (4,5) P2]

These structures are located in the inner lipid monolayer of the plasma membrane.

Structure 3 forms the diacylglycerol and IP3

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10
Q

Where is the IP3 receptor located in the cell and its function?

A

Located in the ER membrane

it is an allosterically coupled ion channel increase [Ca2+] by plasma membrane entry or ER release

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11
Q

What are the 3 factors that are needed for full activation of PKC? Where are they located and their mechanism?

A

DAG (binds C1A and C1B)

Ca2+ (bind C2)

Phosphatidylserine (major membrane lipid; binds C2)

This happens inside the cell

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12
Q

What is a pseudosubstrate and how is this related to the regulation of protein kinases?

A

Psuedosubstrate resembles preferred substrate RXXS/TXR)

Binds stably within a catalytic domain (catalysis of the true substrate leads to product dissociation)

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13
Q

What are these tumor promoters:

Phorbol esters

and

okadaic acid?

A

Phorbol esters –> sufficient to activate many forms of PKC (stuck accelerator (PKC activation)).

Okadaic acid is a protein phosphatase inhibitor from marine dinoflagellate, cause diarrhea by increasing phosphorylation that leads to reduced Na+ uptake and increased Cl- secretion by intestinal cells (broken brake (PP inhibition)).

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14
Q

True or False

Pi can also serve as binding sites for proteins containing pleckstrin homology domains.

A

True

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15
Q

______________ -ubiquitous Ca2+ binding protein that play a key role in many Ca2+ signaling pathways.

Hints:

Likely present in all cells in all vertebrates

Three different ___________ genes in humans-all encode identical 149 a.a. proteins

100% conserved between all vertebrate species (other species also have multiple gemes)

A

Calmodulin (CaM)

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16
Q

What are two different mechanisms for Cam regulation of target protein function?

A
  1. Only active (Ca2+ bound) CaM is able to bind targets (the inactive form is not bound to targets)
  2. Inactive (ca2+ free) caM is prebound to targets, experts effect upon Ca2+ binding
17
Q

Explain the mechanism of CamKII activation by Ca2+

A