1.4 Phys cAMP, FA, IPs Flashcards
adipose tissue lipolysis is catabolic or anabolic?
catabolic
the first step of adipose lipolysis to catalyzed by?
TAG lipase, aka hormone sensetive lipase (HSL)
epi, norepi, glucagon and ACTH activate? how?
HSL via phosphorylation
insulin inactivates?
strongly and rapidly inactivates HSL by dephosphorylation
what activates HSL?
PKA aka protein kinase A in cAMP transduction
What are the adrenergic receptor? what pathway are they a part of?
nor and epi ALPHA AR=IP3
nor and epi beta AR= cAMP
*** you are using the SAME ligand but bind different receptors
Gs G-mediated protein transduction is always coupled with?
adenylate cyclase and cAMP
what is Gi protein?
inhibitory protein
- completly different set of ligands and receptors
- when a specific ligand binds to a receptor that is linked to Gi, it will INHIBIT adenylate cyclase
What are the affects of adenylate cyclase being inhibited?
inhibits cAMP, which inhibits protein kinase A, which inhibits phosphorylation/activation of downstream pathways
Gi protein is an example of?
an endogenous way your body regulates adenylate cyclase/AMP systems
for both Gq and Gs, its activation does what to alpha subunit?
replaces the GDP with GTP, thus releasing the subunit which then enters membrane and activates CE
what is CE used in Gq?
phospholipase C (PL-C) =IP3
what is CE used in Gs?
adenylate cyclase =cAMP
what does PL-C use as a substrate to make products?
phosphatidylinosital bisphsphate (PIP2)
where does PIP2 come from? made by?
inner leaflet of plasma membrane MADE BY phosphatidylinosital kinases!
what are 2nd messengers in Gq?
DAG, Ca+, IP3
what does DAG do in Gq?
activates protein kinase C
do NOT confuse with PKA found in Gs/cAMP
what does IP3 do in Gq?
interacts with cytoplasmic reticulum, thus causing an increase in calcium
what does most of the ca+ as a 2nd messenger do in Gq?
binds to calmodulin to complete the enzyme
*this activates it, causing it to phosphorylate its targets
some proteins are linked directly to? what activates it?
channel proteins
*the acitvation and interaction with alpha subunit
what is membrane signal transduction?
info from EXTRAcellular signal is tranmitted across the membrane
*only info crosses, activates 2nd messenger
alpha subunit interacts with CE how?
by entering membrane WITH GTP
Once active, CE does what?
converts a specific substrate molecule to a specific 2nd messenger
what is the 2nd messenger produced by adenylate cyclase?
cAMP
cAMP signal amplification pathway is an example of?
a G-mediated membrane signal transduction
G-mediated membrane signal transduction pathways ALL consist of?
1) specific ligand
2) 7 transmembrane receptors
3) G-protein
4) catalytic enzyme
5) second messengers
what converts active cAMP to AMP?
phosphodiesterase
what inhibits phosphodiesterases?
xanthines
examples of xanthines?
caffiene (coffee)
theophylline (tea)
theobiomine (chocolate)
PKA is active when it is?
phosphorylated
ligands are typically lipophobic or liprophilic?
lipophobic; unable to cross membrane
