Cell signalling and disease

Question 1

What are 5 S’s of Receptors

Answer 1

1. Structure– The shape or conformation of the receptor initiates the signalling event
2. Specificity– Most receptors are specific for an individual ligand (or highly related versions of a ligand)
3. Sensitivity– Relates to how tight the interaction is between a receptor and its ligand
4. Saturability– Relates to the number of receptors on the cell surface
5. Signal transduction– the intracellular consequences of receptor binding

Question 2

What are the G alpha protein family?

Answer 2

*Gs (Stimulatory)
* Gi (Inhibitory)
* Gq (alpha-adrenergic)

Question 3

What does the gS protein do?

Answer 3

• activates adenylatecyclase
• increases production of cAMP

Question 4

What does the Gi protein?

Answer 4

-Activates phosphodiesterase
-Breaks down cAMP

Question 5

What ligand binding domain?

Answer 5

A strong affinity for specific ligands - allows different ligand that bind to the same receptor to evoke particular cellular responses.

Question 6

What is the transmembrane domain?

Answer 6

Series of hydrophobic AA tethers receptor to cells membrane

Question 7

What is the cytosolic enzyme domain

Answer 7

Intracellular domain is an enzyme or interacts directly with an enzyme

Question 8

What are the different types of tyrosine Kinase?

Answer 8

Receptor tyrosine kinase
Tyrosine kinase associated receptors
Histidine kinase associated receptors
Receptor tyrosine phosphates
Receptor guanlyl cyclase’s

Question 9

What are the different types of receptor tyrosine kinases names?

Answer 9

Egf- epidermal
Ngf- nerve
Pdgf-platelet derived
Fgf-fibroblast
Vegf-vascular endothelial

Question 10

What is fibroblast growth factors?

Answer 10

Mutations in FGFR1 can cause pfeiffer syndrome causing limb defects by premature fusion of the cranial sutures resulting in abnormal skull and facial shape

Question 11

Key information about insulin?

Answer 11

-Causes the addition of phosphate group to tyrosines on certain proteins within the cell

-insulin binds to tyrosine kinase receptor

• The substate proteins that phosphorlyared by insulin receptors include a protein called IRS-1
• IRS-1 binding and phosphorylation = increase in high affinity glucose transporter

Question 12

How does Gs protein coupled receptor work?

Answer 12

1. A peptide hormone binds to the G protein receptor which changes the shape and forms Gs protein
2. The Gs has GDP bounded to it but this is removed and replaced with GTP which activated the Gs protein
3. The activated Gs and GTP bounded bind to the adenylate cyclate enzymes which activates the enzyme
4. The adenylate cyclate will use its the GTPase to break down the GTP and covert it into GDP (Normal)
5. GS has GDP bounded to it again and it converts ATP to cAMP which activates the PKA
6. Pka is the phosphorylation of protein e.g channel protein, the PKA adds a phosphate group allowing thing in and out of the channel