G Protein Linked 2nd Messengers Flashcards
What are the three G proteins, and what are their basic function?
Gs: Increase cAMP
Gi: Decrease cAMP
Gq: Activation of Phospholipase C
If Gq is activated, what are the cascade of events that follows?
Increased Phospholipase C
This releases IP3 and DAG from PIP2 (phospholipid phosphotidylinositol bisphosphate)
IP3 releases Ca from Sarco reticulum
Ca with DAG activates PKC
Which ANS receptors have Gs proteins?
B1 & B2...... (catecholamines) D1.......... (in renalvasculature-->vasodilation) H2 .........(Histamine) Glucagon Prostacyclins Some Serotonins
Remember these all activate adenylyl cyclase
Which ANS receptors have Gi proteins?
M2……….(Ach)
a2………..(adrenoreceptors)
D2………..(important in CNS)
Some serotonin and opioids
Think the inhibitor is MAD X2
They all inhibit AC
Which ANS receptors have Gq proteins?
M1 & M3……….(Ach)
a1………………….(Norepi)
Angio II
Some serotonin
MaM 113
Where is M1, M3 and a1 effective
M1–>CNS
M3–>peripheral autonomics
a1–>on blood vessels, activated by norepi and ep and controls BP
What are the 4 sympathetic receptor types?
a1
a2
B1
B2
What is the major function of a1 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Norepi & Epi
Function:
Increase
-vascular s. muscle contraction
-pupillary dilator muscle contraction (mydriasis)
-intestinal and bladder sphincter muscle contraction
Protein Class: Gq
Receptor Type: Sympathetic
What is the major function of a2 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Norepi & Epi (higher affinity for norepi)
Function: Decrease -Sympathetic outflow -Insulin release -Lipolysis
Increase
-platelet aggregation
Protein class: Gi
Receptor Type: Sympathetic
What is the major function of B1 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Catecholamines
Function: Increase -HR -Contractility -Renin Release -Lipolysis
Protein Class Gs
Receptor Type: Sympathetic
What is the major function of B2 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Catecholamines
Function:
- Vasodilation
- Bronchodilation (s. muscle relax’n in bronchi)
- Increase:
- HR
- Contractility
- lipolysis
- insulin release
- uterine tone (tocolysis)
- ciliary muscle relaxation
- aqueous humor production
Protein Class: Gs
Receptor Type: Sympathetic
What is the major function of M1 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Ach
Function: CNS, Enteric Nervous System
Protein Class: Gq
Receptor Type: Parasympathetic
What is the major function of M2 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Ach
Function:
-Decrease HR and contractility of atria
Protein Class: Gi
Receptor Type: Parasympathetic
What is the major function of M3 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Ach
Function:
- Increase:
- Exocrine Gland Secretions (lacrimal, salivary, gastric)
- Bladder Contraction
- Bronchoconstriction
- Pupillary sphincter muscle contraction (miosis)
- Ciliary muscle contraction (accommodation)
Protein Class: Gi
Receptor Type: Parasympathetic
What is the major function of D1 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Dopamine
Function:
-Relaxes renal vascular s. muscle
Protein Class: Gs
Receptor Type: Dopamine
What is the major function of D2 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Dopamine
Function: Modulates transmitter release, especially in brain
Protein Class: Gi
Receptor Type: Dopamine
What is the major function of H1 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Histamine
Function:
- Increase
- Nasal and bronchial mucus production
- Vascular permeability (duh)
- Contraction of bronchioles
- Pruritis
- Pain
Protein Class: Gq
Receptor Type: Histamine
What is the major function of H2 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Histamine
Function: Increase gastric acid secretion
Protein class: Gs
Receptor Type: Histamine
What is the major function of V1 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Vasopressin
Function: Increase vascular smooth muscle contraction
Protein Class: Gq
Receptor Type: Vasopressin
What is the major function of V2 receptor and what is it’s ligand? What is it’s protein class, and what receptor type is it?
Ligand: Vasopressin
Function:
-Increase H2O permeability and reabsorption in the collecting tubules of the kidney (V2 is found in the 2 kidneys)
Protein Class: Gs
Receptor Type: Vasopressin
What is the mnemonic for the receptor types?
Qiss (sympathetic a1-B2) and
qiq (para M1-M3) til ur
siq (dopa D1/2 and H1) of
sqs (H2, V1 and V2)
What is the mnemonic for the Gq receptor?
HaV 1 M&M (or 3)
H1, a1, V1, M1, and M3
