Class Project
• 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 cells
Muscle cells
Fat cells
Class Project
• Insulin
 Gene is located on chromosome 11 at locus 11p15.5
• Gene ID: 3630
• Gene Symbol: INS
Class Project
D chain
• Insulin
(30 AA)
 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 AA
Insulin = 51 AA
C chain
(30 AA)
A chain
(21 AA)
B 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
In Class Activity: Protein Synthesis
• 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 Translation
2.
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 Editing
3. Perform the edits shown in the slides
•
•
Form two disulfide bonds
Remove the D chain and then the C chain