Signaling II Flashcards
What is the Beta-adrenergic Receptor Signaling pathway?
- Hormone (Epinephrine or glucogon) is released and it binds to the receptor
- Stimulates receptor changing
a. GDP released, GTP attaches - Alpha subunit activates Adenylate Cyclase
a. This catalyzes the ATP to cAMP reaction - cAMP (second messenger) reacts with PKA
a. activates PKA, Puts phosphates on GS and PK
b. Activates Phosphorylase Kinase (PK-P)
c. Deactivates Glycogen Synthase (GS-P) - Phosphorylase Kinase (PK) puts a phosphate on Glycogen Phosphorylase (GP-b)
a. Activates Glycogen Phosphorylase (P-GP-a) - (Glycogen Phosphorylase) P-GP-a
a. Stimulates the break down of Glycogen to release glucose-1-phosphate
What is involved in turning off Beta-adrenergic Receptor Signaling pathway by using the B-Adrenergic Receptor?
If the receptor gets stuck, there is an enzyme called a G-protein Receptor Kinase that puts a phosphate on the receptor (cytoplasmic side). A protein named arrestin binds to the phosphate and covers it up so it makes it so that the G-protein can no longer interact. This favors endocytosis
What is involved in turning off Beta-adrenergic Receptor Signaling pathway by using the G-Protein?
Auto-regulation: it controls itself because it is an inefficient enzyme.
It inefficiently catalyzes inherent GTPase activity
Hydrolysis occurs, a phosphate is lost, GTP to GDP. Then a beta and gamma subunits bind to it again.
What is involved in turning off Beta-adrenergic Receptor Signaling pathway by using the cAMP?
Phosphodiesterase enzyme
It breaks down cAMP to AMP
Phosphodiesterase is inhibited by Caffeine. So if cAMP is not broken down you up your blood glucose.
What is involved in turning off Beta-adrenergic Receptor Signaling pathway by using the PKA?
If you don’t have cAMP then you can’t activate PKA
What are Receptor Tyrosine Kinases (RTKs)? What do they play a role in?
RTKs are membrane bound proteins that phosphorylate tyrosine residues in other proteins.
RTKs play a great role in decisions of whether the cell divides.
What needs to occur Receptor Tyrosine Kinases (RTKs) to activate?
For most RTKs, they must dimerize to be active, and binding of the hormone causes that. Dimerization is important for activity.
What happens when (RTKs) bind to hormone?
When they bind to hormone, they come together and causes them to auto phosphorylate
That causes several phosphates to be put on at the bottoms.
This activates the tyrosine kinase
What are phospho-tyrosines targets for?
The phospho-tyrosines are targets for binding by cellular proteins.
The cellular proteins have specific domains called SH2 that recognize the phospho-tyrosines
The result is that the signal is now inside the cell
What is the exception for RTKs- Insulin receptors?
Exception: It doesn’t require insulin to dimerize since it is already a dimer
Binding of insulin activates auto-phosphorylation of tails
What happens when (RTKs) binding of insulin activates auto-phosphorylation of tails?
Stimulate GLUT4 Movement in cytoplasm
It moves a glucose transport protein to the cell membrane
This will allow it to move glucose in
Glucose is a poison as far as your body is concern. Gives osmotic shock to cells
Inside the cell, the cell makes it into glycogen. Causing Blood glucose levels fall
Stimulates activation of phosphoprotein phosphatase.
What does the Beta- Adrenergic Pathway do to your blood glucose levels?
Glycogen breakdown
Stimulates release of glucose
o Blood Glucose levels rise
What does the Insulin receptor pathway
do to your blood glucose levels?
Glycogen Made
o Blood Glucose levels fall
What are Epidermal Growth Factor(RTKs)? What do they play a role in?
-Found in the membrane
Involved in Growth, proliferation and cell differentiation
What happens when Epidermal Growth Factor(RTKs) activates?
Starts as a monomer and gets dimerized
It auto-phosphorylates tyrosines in cytoplasmic domain
The phospho-tyrosines are targets for an assembly of a signaling complex
