Insulin

Receptor

Dr. Neel Shah

What are the types of receptors?

What are the examples of ligands acting by tyrosine

kinases?

What are the various actions of insulin apart from

transporting glucose?

The student should be able to recall –

The structure of tyrosine kinase receptor.

How insulin mediates its anabolic effects.

How insulin helps the cell take up glucose.

How this

engine

Works??

Substrate – tyrosine residues present on the activation

segment of the opposite dimerized enzyme.

Transfers PO4 group from the γ PO4 of ATP.

prosthetic group – Mg ion.

Activation segment phosphorylation

Phosphorylation beyond it

Formation of the docking sites

Active tyrosine kinase

INOSITOL INOSITOL 3 PO4

INOSITOL 4 PO4 INOSITOL 3,4 BIS PO4

INOSITOL 4,5 BIS PO4INOSITOL 3,4,5 TRIS

PO4

protein

Kinase B

Inositol 3,4 bis PO4

TSC 2

Rheb

mTOR

Rheb

E-BP

e IF

e IF – eukaryotic initiation factor

E-BP – e IF binding protein

Translation

e IF

mTOR-mammalian target of rapamycin

Rheb – Ras homologue enriched in brain

• eIFmTOR

• 40 S ribosomal kinasemTOR

• Cyclin DProtein

kinase B

Activates Hexokinase

Glycogen synthase

Pyruvate dehydrogenase

Acetyl CoA caboxylase

Inhibits

Glycogen phosphorylase

The gluconeogenesis

enzymes that reverse

glycolysis

Hormone sensitive lipase

A GLUT molecule

Nucle

us

Plasma

membrane

Microtubular

Meshwork

GLUT 4

Actin meshwork

Actinin 4

Docking and fusion-

SNARE protein.

Insulin

Whats the first thing that happens to insulin receptor

when insulin binds to it?

1. Dimerization

2. Bridging of the tyrosine kinase domains

3. Activation of protein kinase B

The completely phosphorylated intracellular portion of

insulin receptor acts as a docking site for?

1. mTOR

2. IRS

3. GLUT 4

How does insulin affect GLUT 1 vesicles?

1. Brings them to the surface.

2. Increases synthesis of GLUT 1 mRNA.

3. No effect.