6. Pharmacodynamics Iii - Receptors And Signal Transduction

Front 1

Why is Signal transduction important?

Back 1

Because it is how cells communicate within multicellular organisms.

Front 2

What are 3 functions that cell signalling is essential for?

Back 2

-Development
-Coordination of metabolism
-Motility

Front 3

What 3 steps have to occur for a signal to induce a cellular response?

Back 3

1. Signal needs to get across the plasma membrane
2. Signal has to be transduced through cytoplasm to the nucleus
3. Signal has to induce specific genes to be expressed

Front 4

What gets the signal through these three steps?

Back 4

Receptors and intracellular signaling

Front 5

What are the 2 Types of Cell signalling molecules?

Back 5

1. Secreted molecules
2. Membrane-bound molecules

Front 6

What is the general mechanism of secreted molecule signalling?

Back 6

Signalling molecules are secreted and diffuse to the target cell

Front 7

What are the 4 types of Secreted signalling?

Back 7

-Paracrine
-Autocrine
-Synaptic
-Endocrine

Front 8

Which of the secreted signalling mechanisms is long range?

Back 8

Endocrine

Front 9

How does membrane-bound molecule signalling work?

Back 9

Cells with transmembrane proteins with an extracellular domain act as ligand for receptors on target cells.

Front 10

So which type of cell signalling requires direct contact between cells?

Back 10

Membrane-bound

Front 11

What are the 4 main receptor types? Which are intracellular? Which are membrane bound?

Back 11

1. Intracellular Steroid receptors
2. Membrane bound Ion channels
3. Membrane bound GPC receptors
4. Membrane bound enzyme linked receptors

Front 12

What are the ligands for intracellular steroid receptors?

Back 12

Small hydrophobic signalling molecules

Front 13

What are 4 specific signalling molecules that bind steroid receptors?

Back 13

1. Steroid hormones
2. Thyroid hormones
3. Retinoids
4. Vitamin D

Front 14

How do intracellular steroid receptors function after they are bound by ligand?

Back 14

As ligand-activated transcription factors.

Front 15

Where do the intracellular steroid receptors bind to their ligand?

Back 15

In the cytosol or nucleus

Front 16

How many domains do intracellular steroid receptors have, and what is each?

Back 16

Three:
1. Hormone-binding site
2. DNA-binding domain
3. Transcription-activating domain

Front 17

What are the small hydrophobic signaling molecules (S) for Intracellular steroid receptors carreid by in the blood?

Back 17

Protein carriers - CBG

Front 18

What happens when CBG releases S?

Back 18

It diffuses through the plasma membrane

Front 19

What does S do upon entering the cytosol?

Back 19

Binds its specific receptor (GR)

Front 20

Where are the hormone receptors located?

Back 20

Either in the cytosol or nucleus

Front 21

What happens to the GR when the S binds to it?

Back 21

It induces a conformation change which activates the receptor.

Front 22

What does an activated intracellular steroid receptor do?

Back 22

Binds to hormone response elements GRE on DNA with high affinity

Front 23

Where is the GRE found?

Back 23

Near the promoter region of a target gene

Front 24

What are the 2 ways in which a GRE can regulate gene expression?

Back 24

1. Positively
2. Negatively

Front 25

How does a GRE regulate gene expression positively?

Back 25

By stabilizing the binding of transcription factors

Front 26

How does a GRE regulate gene expression negatively?

Back 26

By repressing the binding of transcription factors.

Front 27

How many genes are generally affected by activated steroid receptors binding to their GRE?

Back 27

Only a small number