Hormone Action & Signal Transduction Flashcards
effect of glucocorticoids
accelerated gene transcription
effect of thyroid hormone
activation of gene transcription
where does hormone-receptor interaction happen in Group I hormones/lipophilic hormones?
cytoplasm, nucleus
G(s) stimulates
adenylyl cyclase
G(i) inhibits
adenylyl cyclase
G(q) stimulates
phospholipase C
what happens once adenylyl cyclase has been stimulated?
cAMP nucleotide is formed from ATP.
1st intracellular signal recognized in mammalian cells
cAMP
adenylyl cyclase composition
receptor - R(s) or R(i)
regulatory complex - G(s) or G(i)
how does cholera affect the alpha subunit of GPCR?
it modifies alpha subunit, blocking hydrolysis of GTP back to GDP; therefore, a-GTP remains in active form.
cholera toxin: a-GTP always active results to?
severe diarrhea due to persistently high cAMP levels
CFTR channels are stimulated to open –> Cl- + Na + Water leave cell
Hormones that inhibit adenylyl cyclase (4)
- acetylcholine
- a2 adrenergics
- angiotensin II
- somatostatin
after cAMP is produced from ATP, what happens next? (GPCR)
cAMP activates protein kinase A
protein kinase A composition
2 regulatory subunits (R2)
2 catalytic subunits (C2)
active C subunit of PKA catalyzes?
transfer of gamma phosphate of ATP to serine or threonine residue –> PHOSPHORYLATION
how is PKA activated? (GPCR)
cAMP binds to regulatory unit of cAMP –> R2C2 dissociate, activating C2
enzymes that terminate physiologic response of activated GPCR
phosphatases
phosphodiesterase
how does phosphodiesterase terminate physiological response of activated GPCR?
hydrolyzes cAMP to 5’-AMP
what peptides are produced by cardiac atrial tissues?
atriopeptins
atriopeptins bind and activate?
guanylyl cyclase (increasing cGMP levels)
elevated cGMP due to atriopeptins result to
natriuresis
diuresis
vasodilation
inhibition of aldosterone secretion
what other substances activate guanylyl cyclase?
nitroprusside nitroglycerine nitric oxide na nitrite na azide
can sildenafil (viagra) be given to pts taking nitrates?
no b/c it will potentiate to the vasodilating effect due to increased cGMP level.
IKK complex composition (NF-KB)
2 alpha subunits
2 beta subunits
2 gamma subunits
