Biochemistry G Proteins

what tissues do alpha 1 receptors distribute to

• vascular smooth muscles

• visceral smooth muscles

what is the mechanism of action for alpha 1 receptors

• Gq-protein couple activates Phospholipase C, IP3+DAG

what is the agonist potency for alpha 1 receptors

epinephrine>norepinephrine»isoproterenol

what are the physiological effects of alpha 1 receptors

• smooth muscle contractions

• gluconeogenesis

• vasoconstriction

name the agonists for alpha 1 receptors

• norepinephrine

• phenylephrine

• methoxamine

name some antagonists for alpha 1 receptors

• doxazosin

• phentolamine

• prazosin

where are alpha 2 receptors distributed

• presynaptic terminals

• pancreas

• platelets

• ciliary epithelium

• salivary glands 

describe the mechanism of action for alpha 2 receptors

• Gi-protein couple inhibits adenyl cyclase 

what is the agonist potency for alpha 2 receptors

epinephrine>norepinephrine»isoproterenol

what are the physiological effects of alpha 2 receptors

inhibits release of neurotransmitters

name the agonists for alpha 2 receptors

• clonidine

• monoxidine

name the antagonists for alpha 2 receptors

• yohimbine

• idazoxan

• tolazoline

where are beta 1 receptors distributed

• heart

• kidney

• some pre-synaptic terminals 

what is the mechanism of action for beta 1 receptors

• Gs protein couple activates adenyl cyclase and PKA

what is the agonist potency for beta 1 receptors

isoproterenol>epinephrine>norepinephrine

what are the physiological effects of beta 1 receptors

• increased heart rate and renin secretion

name the agonists for beta 1 receptors

• isoproterenol

• norepinephrine

• dobutamine 

name the antagonists for beta 1 receptors

• propranalol

• metroprolol

• atenolol

where are beta 2 receptors distributed

• visceral smooth muscles

• bronchioles

• liver

• skeletal muscles

what is the mechanism of action for beta 2 receptors

Gs-protein couple activates adenyl cyclase, PKA, and calcium channels

describe the agonist potency for beta 2 receptors

isoproterenol>epinephrine»norepinephrine

what are the physiological effects of beta 2 receptors

• vasodilation

• bronchodilation

• inhibited insulin secretion 

name the agonists for beta 2 receptors 

• isoproterenol

• salbutamol

• salmeterol

• albuterol

• formoterol

• terbutaline

• levalbuterol

name the antagonists for beta 2 receptors

• propranolol

• ICI-118,551

• nadolol

• butoxamine

where are beta 3 receptors found

adipose tissue

what is the mechanism of action for beta 3 receptors

• Gs protein couple activates adenyl cyclase and PKA

describe the agonist potency for beta 3 receptors

isoproterenol=norepinephrine>epinephrine

what are the physiological effects of beta 3 receptors

• increased lipolysis 

name the agonists for beta 3 receptors

• isoproterenol

• amibegron

• solabegron

name the antagonist for beta 3 receptors

SR59230A

what is epinephrine used for

treatment for anaphylaxis

what is isoproterenol used for

used for the treatment of:

• bradycardia (slow heart rate)

• heart block

• asthma

what is propranolol used for

used to treat:

• hypertension

• anxiety

• panic 

are g proteins enzymes

yes

are g proteins active when GTP is bound

yes

are g proteins active when GDP is bound

• no

• think D for dead

which g proteins stimulate adenylate cyclase

Gsa

what g proteins inhibit adenylate cyclase

Gi

what are the receptors and second messenger for Gs proteins

receptors:

• beta adrenergic receptor

• endothelin receptor 2

• glucagon

major second messenger:

• increased cAMP

name the receptors and second messengers for Gi proteins

receptors:

• a2-adrenergic 5-hydroxytrptamine

• acetylcholine

second messenger:

• decreased cAMP

what are the receptors and major second messenger for Gq proteins

receptors:

• endothelin receptor 1

• histamine receptor

• angiotensin receptor 1

second messengers:

• diacylglycerol

• IP3

• increased intracellular calcium

what does guanine nucleotide exchange factor do

• releases GDP, allowing binding of GTP

what is the inactivator protein for g proteins

• GAP

• GTPase-activating protein

• RGS (regulator of G protein signaling)