Biochemistry of Insulin Flashcards
how you insulin kill you
go into hypoglycemic coma
what makes insulin
beta cells in the pancreas, islets of langerhans
what do alpha cells make
glucagon
what do gamma cells make
somatostatin
what do PP cells in the pancreatic islets make
pancreatic polypeptide
what is the counter hormone (starvation hormone) to insulin
glucagon
where in beta cells is insulin synthesised
rough endoplasmic reticulum
describe the process of insulin synthesis
starts as larger single chain preprophormone (preproinsulin)
cleaved to form insulin
what is the structure of insulin
two polypeptide chains linked by disulfide bonds
connecting C peptide (a byproduct of cleavage)
what preparation of insulin is ultrafast/ultra short acting
insulin lispro
what affected how long insulin lasts
position of amino acids- affects how stable it is
what is the most rapidly acting insulin
insulin lispro
how is insulin lispro used clinically
Injected within 15 minutes of beginning a meal
short duration of action- must be used in combination with longer-acting preparation for Type 1 diabetes unless used for continuous infusion
describe the structure of insulin lispro
monomeric, not antigenic
what prep of insulin is ultra long lasting
glargine
when is glargine administered
single bedtime dose
describe the action of glargine
Recombinant insulin analog that precipitates in the neutral environment of subcutaneous tissue
Peakless- prolonged action
how does glucose enter beta cells
GLUT2 glucose transporter (goes down concentration gradient)
what happens to glucose once it enters beta cells
phosphorylated by glucokinase
what senses the amount of glucose that enters a beta cell
glucokinase
what does increased metabolism of glucose lead to
an increase in intracellular ATP concentration
lists the steps of carb metabolism
glucose-6-P
glycolysis (also makes e- and CO2)
acetyl- CoA
TCA cycle
(e- go to oxidative phosphorylation)
=
36 ATP per glucose
what does ATP do in beta cells
inhibits the ATP sensitive K+ channel KATP- causes depolarisation of the cell membrane
what happens when the cell membrane of beta cells depolarises
voltage gates Ca2+ channels open - increase in Ca2+ conc leads to fusion of secretory vesicles within the cell membrane that release insulin