Hormonal Regulation I

Question 1

What is the end product of glycolysis?

Answer 1

Pyruvate

Question 2

What are the two obligate glucose users in the human body?

Answer 2

Brain and RBCs

Question 3

Structure of pro-insulin

Answer 3

alpha chain connected to beta chain via c-peptide

nb: disulfide bonds maintain structure
nb: pro-hormone convertase cleaves pro-hormone in GOLGI

Question 4

What is the main transporter of glucose in the cell?

Answer 4

GLUT2

non regulated, [ ] driven

Question 5

What enzyme is responsible for the conversion of glucose to glucose 6 phosphate?

Answer 5

Glucokinase

Question 6

Mechanism of GLP-1?

Answer 6

GLP-1 secreted by L-cells
Binds to GLP-1R, signals through cAMP/PKA
increases intracellular [Ca2+] leading to insulin secretion
GLP-1 increase beta cell mass and proinsulin gene expression
GLP-1 decresaes gastric emptying and glucagon secretion
GLP-1 is rapidly destroyed by DPP4

Question 7

Mechanism of Sulfonylurea

Answer 7

Binds to SUR subunit of ATP-regulated K+ channel
Enhances ability of ATP to close the channel resulting in greater depolarization
Depolarization leads to high intra Ca resulting in Insulin release

Question 8

Mechanism of alpha2-AR

Answer 8

linked to Gi

decreases cAMP lowers intra [Ca] resulting in lower insulin release

Question 9

Mechanism of parasympathetic

Answer 9

Linked to Gq

IP3–>PKC–> Increase intra [Ca] resulting in insulin release

Question 10

Potent Amino Acid stimulators of insulin release

Answer 10

leucine, glycine, arginine

Question 11

Mechanism of Insulin Receptor

Answer 11

Insulin Receptor is a tyrosine kinase receptor
intracellular portion becomes phosphorylated when bound to insulin
Binds to IRS
IRS gets phosphorylated and activates PI3-K
PI3-K cleaves PIP2 to PIP3
PIP3 actiaves PDK1
PDK1 phosphorylates and activates Akt