4 Flashcards
example of catabolism
stimulation of glycogen breakdown
what is catabolism signalled by?
glucagon in liver
adrenaline in muscles
signal transduction and catabolism?
how does it occur?
via 2nd messengers
cAMP
example of anabolism
stimulation of glycogen synthesis
what is anabolism signalled by?
insulin
signal transduction and anabolism?
how does it occur?
via receptor protein kinase
InsR
what is glucagon?
polypeptide hormone (29AAs) secreted by alpha cells of the pancreas in response to low blood glucose
half life of glucagon?
many minutes in bloodstream
glucagon interacts with what receptor?
GPCR receptor on plasma membrane of target cells
signalling cascade is initiated by release of 2nd messenger / cAMP, which is triggered by what?
G protein, adjacent to GPCR
signalling cascade leads to…
(2)
phosphorylation of:
- glycogen phosphorylase
- hormone sensitive lipase
and other effects which impact on suppression of fatty acid and glycogen synthesis
net effect of catabolism:
energy usage
signals the “hungry” state
what is cAMP?
molecule that acts as a 2nd messenger
derived from ATP
an activator of protein kinase A
how is cAMP degraded?
by phosphodiesterases to 5’AMP
what effector molecules does cAMP interact with?
they all begin with C
cyclic nucleotide gated ion channels
cAMP regulated G protein exchange factors
cAMP dependent protein kinase
what is insulin?
polypeptide (51AAs) secreted by beta cells of pancreas in response to high blood glucose conc
what does insulin signal / stimulate?
stimulates glucose uptake into cells, storage of fuels / energy, and synthesis of protein within cells
half life of insulin?
many minutes in bloodstream
what receptors does insulin interact with?
Tyr kinase receptor / Insulin receptor (IR) on surface of target cells
signalling leads to phosphorylation of…
- glycogen synthase
- ribosomal S6
- protein kinase B
- enzymes involved in fatty acid synthesis
net effect of anabolism:
energy storage
why do we see the symptoms of type-2 diabetes?
in obesity, abnormal inflammatory signals stop the normal IRD signalling process from working properly
abnormal cell signalling in obesity leads to…
increased visceral adipocyte-linked signalling
increased visceral adipocyte-linked signalling increases…
increases blood…
- glucose conc
- insulin conc
- lipid conc
+ induces chronic inflammation
= insulin resistance, hyperglycaemia, dyslipidemia
