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38 Cards in this Set

  • Front
  • Back
what are the three important H for short term metabolic regulation
what releases it
tissues it acts on
chemicals is acts through
what it causes(glycogenolysis etc)
where: adrenal medula released in response to stress

tissues: adipose liver muscles

chemicals activated: cAMP and Ca

function on metabolism: increases glycogenolysis lipolysis and glycolysis
what releases it
where it acts
how it acts (chemicals is acts through)
what these chemicals do for metabolism
produced from: alpha pancreatic cells in rsps to low glucose ad insulin blood levels

tissues: liver adipose

chemicals activated: cAMP

response: increase glycogenolysis, gluconeogenesis and lipolysis
decrease glycolysis
what releases it
where it acts
how it acts (chemicals is acts through)
what these chemicals do for metabolism
from: beta pancreatic cells in rsps to high blood glucose

tissues: liver muscle adipose

chemicals activated: tyrosine kinase and phosphatidylinositol 3,4,5-P3
it decreases cAMP

function: increases glucose transport, fatty acid synthesis, and glycogen synthesis
decreases lipolysis
how does glucagon and epi use cAMP?
bind membrane receptors which activate adenylate cyclase which makes cAMP

cAMP binds regulatory units of PKA and releases catalytic untis which can then phosphorylate things
What other receptors can epi bind?

DISCREPANCY PAGE 179, norepi binds alpha to initiate IP3 DAG pathway through G alpha q, EPI works on beta adrenergic to INCREASE cAMP
alpha adrenergic
these activate phospolipase C which turns PIP2 to IP3 and DAG (diacylglycerol)

IP3 releases Ca stores which bind to calmodulin making an active protein kinase

DAG stays in membrane and activates PKC which is a membrane protein that can phosphorylate things just like PKA
when Ca is released, does it bind calmodulin and then the whole complex activates PKA? how does it activate PKA, or is it just Ca or just calmodulin?
how does insulin use phosphatidylinositol 3-4-5-P3?
insulin binds receptor, receptor activates phosphotidylinositol-3 kinase

kinase makes PIP3 from PIP2

PIP3 activates PKB

PKB phosphorylates things
is PKB a membrane bound messenger?
what three things does protein kinase B do?
inhibits glycogen synthase kinase 3 (so glycogen synthase isn't phosphorylated, no P = active)

activates glycolysis in muscle

through Akt see increased GLUT4 to membrane (glut4 is the only insulin dependent transporter it is found in muscle and adipose)

inhibits lipolysis in adipose tissue
pop quiz

what does Ca and calmodulin-like subunit regulate in glycogen regulation?
activates phosphorylase kinase

kinase activates glycogen phosphorylase by P'ing it

glycogen phosphorylase splits off gluc units untill the dextrin limit
if you phosphorylate glycogen phosphorylase it activates it and then glycogen can be degraded for glucose

BUT if you phosphorylate PDH at E1 it inactivates it, PDH helps to break down glucose

. . . why??
Describe glucose uptake in the brain
TRansporter: low Km
insulin independent

product inhibition of hexokinase

glucose use controlled by product G6P
Describe glucose uptake in the liver
high Km
insulin independent

need high blood gluc to uptake

glucokinase shows no product inhibition, GKRP
Describe glucose uptake in tissues like muscle
low Km
insulin dependent

insulin causes transporters to move from stores to the plasma membrane
generally how does glucose into cells?
facilitated diffusion

in kidney and intestinal epithelia it can be taken up against [grad], cotransporter Na-gluc

normal blood glucose levels
70-110 mg/dl
GLUT 1-4
which ones are insulin dependent
only GLUT4
where is GLUT 1 found
RBS and fetal tissue
GLUT 2 is found where
liver and beta-cells
glut 3 is found
glut 4 is found
muscle and adipose
GLUT4 increase in plasma membrane
insulin activates Akt which somehow leads to glut4 fusion into membrane, this is a short term regulation

skeletal muscle exercise increases GLUT4 in membrane (through AMP activated protein kinase) also short term

long term - exercise leads to increased GLUT4 gene expression and hence higher levels of GLUT4 protein
Glucose phosphorylation

hexokinase - inhibited by?
explain the regulation of glucokinase
inhibited by GKRP (glucokinase regulatory protein)
GKRP is facilitated in binding by F6P
GKRP-glucokinase complex is translocated into the nucleus of the cell where it waits.
F1P reverses inhibition(disinhibits)

insulin causes upregulation of glucokinase gene??
glucose utilization in the brain is controlled by?
controlled by product
glucose utilization is controlled by what in muscle
by blood glucose concentration and product (G6P)

insulin causes more uptake
glucose utilization is controlled by what in the liver
blood glucose concentration
once glucose is taken up in a cell what types of pathways can it take
can becomes glycogen
can go into glycolysis and be used
can go into the hexose monophosphate pathway
what takes G6Phosphate back to glucose
Liver Pyruvate kinase
Also regulated covalently by PKA phosphorylation(active vs inactive)

allosteric and covalent regulation are additive

allosteric can shift the equilibrium in favor of active or inactive
Pyruvate kinase, active or inactive when P'd?
describe the structure of pyruvate kinase
each subunit has 4 domains
active site between A and B
subunit contact eachother in C domain
N domain after C
What is different about liver isoform of pyruvate kinase in terms of structure
serine residue in N terminal domain where phosphorylation occurs, causes conformational change in the tetramer and increases Km/sensitivity to other negative allosteric regulators
questions page 38!
Pyruvate kinase deficiency
often effects RBC's cause they rely on glycolysis, mutation in Pyruvate kinase gene

chronic hemolytic anemia
List PFK1's
product inhibition
feedback inhibition
homotropic allosteric inhibition
heterotropic allosteric inhibition
product inhibition - F1,6P? no
feedback inhibition - 3phosphoglycerate
homotropic allosteric inhibition(substrate inhibition) - none, it is upregulated by substrates like F6P and ATP
Heterotropic allosteric inhibition(allosteric modulator is something other than the protein's substrate.
) - ATP, citrate
does phosphorylation of pyruvate kinase effect Km or Vmax
Km (competitive inhibition, Vmax is unchanged)

(non-competitive reduces
(Vmax) without changing the apparent binding affinity of the catalyst for the substrate)