Module-Insulin Flashcards
Insulin is a (steroid/peptide) hormone synthesized in the (alpha/beta/delta) cells of the pancreas
Peptide; Beta
Pattern of Insulin activation from precursor molecules
Pre-Pro-Insulin–> Pro-Insulin–> Insulin
Conversion of Pre-Pro-Insulin to Pro-Insulin occurs where in the cell
Rough Endoplasmic Reticulum
Conversion of Pro-Insulin to Insulin occurs where in the cell
Secretory vesicles (cleave off C-peptide)
What is cleaved from the Pro-Insulin molecule to convert it into Insulin
C-peptide
Insulin is composed of _____ chains held together by ___________________ bonds
2 (alpha and beta); disulfide
Stimuli for Insulin release (4 total)
Inc. blood sugar
Inc. amino acids
Parasympathetic NS
Incretins (GLP-1 and GIP)
Glucose enters Beta cells via GLUT (1/2/3/4) transporters to trigger Insulin release
GLUT 2
How does Glucose entering Beta Cells trigger Insulin release
ATP generated–> K channels close–> Ca channels open–> Ca enters–> Insulin granules fuse w/ membrane and release
Insulin binds to (internal/external) receptors of target cells
External (remember it’s a peptide, so can’t enter cell)
The Insulin receptor is a _________________ ___________ that activates Ras and P13K mediated pathways
tyrosine kinase
Insulin acts mainly on what tissues
Liver
Muscle
Adipose
*NOT brain, shouldn’t have to rely on Insulin, needs constant supply
Insulin’s net effect is to (increase/decrease) glucose levels
Dec. glucose levels
The Insulin receptor has what subunits?
2 alpha and 2 beta (linked by disulfide bonds)
Insulin binds to (alpha/beta) subunits of the receptor
Alpha
*beta causes autophosphorylation
(Alpha/Beta) subunits of the Insulin receptor cause autophosphorylation
Beta
Purpose of Insulin receptor autophosphorylation
Activate catalytic activity and trigger internal response
Insulin activates what metabolic pathways? (4 total)
Glycolysis (liver, muscle and adipose)\ Glycogen synthesis (liver and muscle) Protein synthesis (muscle) FA synthesis (liver and adipose)
Insulin stimulates GLUT4 translocation in what tissue?
Muscle (for glucose uptake –> glycolysis and glycogen synthesis)
