• Insulin Produced by beta-cells in pancreas Hormone involved in regulation of blood glucose levels

• tells liver, muscle and fat cells to take up glucose from the blood and store it as glycogen (liver cells, muscle cells) or fat (fat cells)

Liver cellsMuscle cells Fat cells

Class Project

• Insulin Gene is located on chromosome 11 at locus 11p15.5

• Gene ID: 3630• Gene Symbol: INS

Class Project

B chain(30 AA)

A chain(21 AA)

• Insulin A single gene is

responsible for preproinsulin

Undergoes extensive protein modifications following translation to remove the D chain and C chain regions

The remaining A chain and B chain regions form insulin

Preproinsulin = 106 AAInsulin = 51 AA

C chain(30 AA)

D chain(30 AA)

Class Project

• Insulin Can be found in protein data bank at:

http://www.pdb.org/pdb/explore/explore.do?structureId=3E7Z

Can also be viewed at:http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/pancreas/insulin_struct.html

Active form = monomer composed of A chain and B chain•The A chain is composed of 21 amino acids•The B chain is composed of 30 amino acids•The A and B chains are held together by two disulfide bonds

Inactive form (stored form) = hexamer held together by zinc ions

disulfide bonds

Class Project

• Model Transcription 1. Use the RNA nucleotides to construct an mRNA

copy of the preproinsulin gene (be sure to use the correct strand – the one given in the research paper)

• Model Translation2. Translate the preproinsulin mRNA into a

protein by using the nucleotide sequence to place the amino acids in the correct order (write the abbreviation for each amino acid on the little slip of paper)

• Model Protein Editing3. Perform the edits shown in the slides

• Form two disulfide bonds • Remove the D chain and then the C chain

In Class Activity: Protein Synthesis