Receptors and Cell Signaling Flashcards
What kind of signaling does Epinephrine utilize?
Endocrine because it is long distance and a hormone
What kind of signaling does testosterone use?
Paracrine because it acts on neighboring cells and is short lived
What kind of signaling does IL-1 utilize?
Autocrine because it os produced by T-lymphocytes to promote their own replication during an immune response.
Growth Factors do the same thing for cancer cells
What kind of signaling does Heparin binding epidermal growth factor utilize?
Direct/Juxtacrine
What are two hydrophilic receptors and which hormones are involved which each?
GPCR- Glucagon/Epinephrine
Receptor Tyrosine Kinases (RTKs)- Insulin
What are the 2 types of lipophilic receptors?
Cytoplasmic- when hormones bind to this receptor the complex translocates into the nucleus where it binds to a specific DNA sequence called the Hormone Response Element (HRE) in the promoter region of genes.
Nuclear receptors- Already present in the nucleus bound t DNA. The hormone allows for interactions with additional proteins and activates the complex.
*(Note that both of these receptors have activity within the nucleus)
Which subunit from GPCR trimeric protein contains GDP when inactive and utilizes Guanine Exchange Factor (GEF) to bind GTP?
Alpha subunit, which utilizes GEF when it binds to the transmembrane GPCR protein
What is the function of Gs in GPCR signaling?
What are the 2 signaling molecules for Gs?
Stimulates adenylate cyclase
Epinephrine- Beta- Adrenergic GPCR Receptor
Histamine
What is the function of Gi in GPCR signaling?
What are the 2 signaling molecules for Gi?
Inhibits adenylate cyclase
Epinephrine/Norepinephrine- Alpha Adrenergic GPCR Receptor
Dopamine
What is the function of Gt in GPCR signaling?
What is the signaling molecule for Gt?
Stimulates cGMP phosphodiesterase
Light- activates Rhodopsin
What is the function of Gq in GPCR signaling?
What is the signaling molecule for Gq?
Activates Phospholipase C
Acetylcholine- activates Muscarinic GPCR Receptor
What is the result of inhibiting cGMP phosphodiesterase? Give an example.
Increases the concentration of cellular cGMP and prolongs its effects for a greater amount of time leading to smooth muscle relaxation and vasodilation. (Viagra)
Describe the effects of coffee.
Inhibits the activity of cAMP phosphodiesterase, leading to the accumulation of cAMP which increases heart rate
Describe how cholera toxin leads to diarrhea.
Consumption of contaminated water leads to the covalent modification of Gs alpha subunits.
ADP ribosylation of Arginine in Gs alpha decreases intrinsic GTPase activity. This leads to Gs alpha remaining active in its GTP bound form and continuously stimulating adenylate cyclase, resulting in overproduction of cAMP.
Increase in cAMP leads to Cl- channels opening in intestinal cells, which leads to water and electrolyte loss
*Make sure to know this is Gs alpha remaining active that causes this
Describe how pertussis is caused.
Pertussis toxin prevents the activation of Gi alpha ADP ribosylation, which prevents activation and dissociation of a subunit from the trimeric G protein complex.
Less inhibition of Adenylyl cyclase leads to overproduction of cAMP.
This leads to whooping cough
