GLUT-4 Translocation Flashcards
describe insulin in fed condition?
source of carbs converted into glucose and carried around blood
in fasting state describe insulin?
to keep glucose levels up we take glucose from other sources
what is the structure of GLIT-4?
c and n terminus inside plasma membrane major cytoplasmic loop 12 transmembrane domains 8 are arranged in circle make aquous pore
describe glut-4 in basal condition?
1 glut4 in membrane and most others inside vesicles intracellular
what happens to glut4 during an insulin burst?
when glucose levels rise, insulin production and this binds to receptors causing signalling cascade
leads to glut4 storage vesicles to insert glut4 into membrane via translocation
snare proteins involved
what happens to glut4 during continuous insulin?
if insulin circulates long enough, glut4 remains in membrane and wont be reuptaken
what are the two glut4 translocation pathways?
nutrient supply triggered energy demand (contraction of muscles)
what is the isulin receptor involved in glut-4 translocation?
classic tyrosine kinase which works as a dimer
describe tyrosine kinase receptors?
alpha subunit extracellular
beta subunit intracellular
alpha binds insulin triggering dimerisation and receptor activation
cross phosphorylation on the beta subunit
what is cross phosphorylation?
alpha attached to beta by disulphide bridges
phosphate added to lysine 1018 on beta domain
regulatory loop, juxtamembrane region and c terminal region
what is the insulin receptor substrate?
insulin ligand bound to tyrosine kinase receptor, dimerised then cross phosphorylated -> signalling cascade
what is the function of phosphooinositide-3-kinase?
takes pip2 and adds phosphate to make pip3
p110 and p85
what is akt?
protein kinase b
describe structure of akt/pkb?
ph domain to bind pip3 in membrane
activated by phosphorylation at two locations (thr308 and ser473)
what is as160?
a rab-gap
for the gap/gef cycle
controls glut 4 trafficking
