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22 Cards in this Set

  • Front
  • Back
What is the largest family of cell receptors?
G protein linked receptors (GPLR)
How does Vibrio Cholerae cause disease?
Through the production of cAMP
Describe the serpentine structure shared by all GLPR
Seven hydrophobic stretches through the membrane with amine group in the ECM and the carboxy group in the cytosol.
What is the function of trimeric G proteins?
Serves as relay molecules for GPLR
What does the alpha subunit of the trimeric G protein bind?
Guanyl nucleotide
What is the only subunit of trimeric G protein that does not bind to PM?
Beta subunit
Describe the inactive state of trimeric G proteins.
GDP is bound to G alpha subunit, which is bound to G beta and G gamma. (Trimeric complex)
Describe the active state of trimeric G proteins.
GTP is bound on G alpha, while G beta and G gamma dissociate.
What are the two "flavors" of trimeric G proteins?
Gs - G stimulatory that acts to stimulate target enzyme

Gi - G inhibitory that acts to inhibit target enzyme
Trimeric G proteins functionally couple ________ to ________ to regulate production of ___________
the receptor
adenylyl cyclase
What binds to adenylyl cyclase to activate synthesis of cAMP?
Gs alpha
How do you deactivate G hormone/receptor complex? 2 steps
1. Carboxy terminal tail of the receptor becomes phosphorylated

2. Phosphorylated tail is bound by proteins (arrestins) which sterically block G protein/receptor interaction
What does hydrolysis of GTP do?
Inactivate the trimeric G protein.
What enhances the hydrolysis of GTP?
RGS proteins (regulator of G protein signal)
What does cAMP activate?
PKA (protein kinase A)
What are the two types of PKA and where are they?
Type I - Free in the cytosol

Type II - anchored to membrane
In the nucleus, how does PKA activate transcription?
PKA phosphorylates transcription factor CREB. The phosphorylated CREB will bind to co-activator CBP which will activate transcription.
What is the only means of deactivating cAMP?
Through the actions of PDE (cAMP Phosphodiesterases)
What does PDE change cAMP into?
Give two inhibitors of PDE.
1. Xanthine (caffeine & theophylline)

2. Viagra
T/F - Adrenaline is mediated by cAMP
If blood calcium is low, what hormone is secreted?