Insulin

1
Insulin

• BIOL 4900
• Peter Gadja Background
• Danielle Hiers - Structure
• Katie Peppers Homology/Phylogeny

2
BACKGROUND

• Production
• Produced in pancreas
• Islets of Langerhans
• Uses
• Hormone that signals glucose metabolism
• Uses feedback mechanism
• Causes reduction in appetite
• Organisms
• Insulin is used by all vertebrates as a source of
  metabolic control
• Organisms must have b-cells in pancreas in order
  to produce insulin

3
MECHANISM OF ACTION

• Released when blood-glucose levels are high
• Insulin binds to the cell membrane
• Comprised of an a and b subunit
• a-subunit is on the outside of the cell
• b-subunit is on the inside of the cell
• The b-subunit is a tyrosine kinase and when
  insulin binds it starts a phosphorylation cascade
• GLUT 4 glucose transporters- become excited by
  this and move to bind to the plasma membrane
• Glucose can now diffuse through the membrane

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Reaction requires ATP
Insulin action2 http//www.elp.manchester.ac.uk/p
ub_projects/2000/mnby7lc2/insulin_action2.gif
Subunits held together by disulfide bridges
3) CH_12 insulin GT http//courses.cm.utexas.edu/
jrobertus/ch339k/overheads-2/ch12_insulin-gt.jpg
2) Insulin Binding site http//www.vivo.colostate
.edu/hbooks/pathphys/endocrine/pancreas/insulin_ph
ys.html
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HOW INSULIN RELEASE WORKS IN THE CELL
http//www.apsu.edu/thompsonj/Anatomy2020Physio
logy/2010/201020Exam20Reviews/Exam20520Final2
0Review/insulin.Fig.25.18.jpg
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DISEASES CAUSED BY INSULIN

• Insulin does not cause a disease
• Diseases arise due to lack of insulin
• Resistance to insulin
• Diabetes 1 and 2
• Type 1
• Total lack of production of insulin
• Pancreas has been removed or b-cells damaged
• Type 2
• Resistance to insulin
• Occurs in adults
• Problems with receptor to signaling problems

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CONTROLLING DIABETES

• Type 1
• Insulin replacement therapy
• Synthetic insulin
• Originally purified from pigs and cows
• Produced in mass amounts through recombinant DNA
  techniques
• Healthy diet
• Type 2
• Controlled by diet and monitored
• Both increase your risk for heart disease,
  blindness, nerve damage, and kidney damage

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SPECIAL APPLIACTIONS

• Insulin coma therapy
• 1930-1950s
• Common psychiatric treatment of schizophrenia and
  depression
• Discovered in Germany and immigrated to US before
  WWII
• Insulin given to restrict glucose supply to brain
• causing shock, coma, convulsions
• Replaced by electroconvulsive therapy from
  1950-1980s

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SPECIAL APPLICATIONS

• Intravenous GIK solution
• Decrease mortality rates caused by heart attack
  and postoperative cardiac failure
• High dose used in heart surgery/transplantation
  to induce a heart attack
• Infuse potassium in heart which impairs
  circulation
• Body building
• Most anabolic hormone
• Enhance muscle growth rather than fat
• If sufficient carbs are not consumed in time
  death occurs as a result

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STRUCTURE FOR BOVINE-1APH
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CHARACTERISTICS OF PROTEIN STRUCTURE

• Two non-identical amino acid chains
• Chain A 21 residues
• Chain B 30 residues
• One ligand - 1,2-dichloroethane
• Three disulfide bridges
• No active site present
• Member of insulin-like family
• Not transmembrane

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LIGAND INTERACTIONS

• C2H4Cl2
• Total of 6 residues in Chain B interacting with
  this ligand
• 3 Ser-9 residues
• 1 Val -12 residue
• 2 Glu-13 residues

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STRUCTURAL MOTIFS

• Chain A
• 1 motif , residues 6-21
• Insulin
• Family of proteins that consists of an A and B
  chain linked by 2 disulfide bridges
• Chain B
• 1 motif, residues 27-30
• pkc_phospho_site
• Protein kinase C
• Phosphorylation of serine or threonine residues
  close to the C-terminus

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PREDICTIVE MODELING

• All programs predicted the same number of amino
  acids in each chain

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CHOFAS PREDICTED 2 STRUCTURE
CHAIN A
CHAIN B
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PELE PREDICTED 2 STRUCTURE
CHAIN A
CHAIN B
Chain B there is a very small helix and a very
small b-sheet
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PROTEIN EXPLORER- 2 STRUCTURE
Disulfide Bridges Bridge 1 intrachain bridge
within chain A CYS-6 and CYS-11 Bridge 2
interchain bridge CYS-7 between A and B Bridge 3
interchain bridge CYS-19 (B) and CYS-20 (A)
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MUTATIONS IN THE PROTEIN

• Several mutant sequences were found in ndjinn
• Human growth factor mutant
• Insulin mutant P28, D, chain B
• Insulin human mutant with PHE-24, chain B,
  replaced by Serine
• Many more
• None significantly affected the function of
  insulin

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HOMOLOGY/PHYLOGENY

• Proinsulin precursor
• Peptide links N-terminus of A chain w/ C-terminus
  of B chain
• Synthesized by Rough Endoplasmic Reticulum
• Enzymes outside Golgi convert proinsulin into
  insulin

http//ocw.tufts.edu/data/14/265878/278271_medium.
jpg
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INSULIN IN BIOLOGY WORKBENCH
(Rneteria, Gandi, Vineusa, Helmerhorst,
Mancera, 2008)
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HOMOLOGY/PHYLOGENY

• Significant homologs to Bovine insulin
• Amphioxus
• Zebra fish
• Frog
• Chicken
• Sheep
• Wild Boar
• Squirrel
• Macaque
• Human
• All the above have lt1 E-value in BlastP

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BOOTSTRAP VALUES
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UNROOTED TREE
89.4
70.1
100
89.7
61.9
999.7
99.9
24
ROOTED TREE
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CONSERVED REGIONS
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BOXSHADE
KEY Completely Conserved Identical Similar
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STRUCTURE ALIGNMENTS IN CN3D
VAST did not locate any related structure for
Chain A or B to align
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WHAT DOES IT ALL MEAN?

• Phylogeny begins with insulin producing b-cells
• Amphioxus Protochordate
• Cells confined to region of gut
• Evolutionary accumulation of b-cells in this
  region
• Primitive Vertebrates (Lamprey/Hagfish)
• Collection of endocrine cells in duodenum
• 99 b-cells
• 1 somatic cells
• b- cells are the pancreatic cells that produce
  insulin

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WHAT DOES IT ALL MEAN?

• Insulin has a significant role in the metabolism
  of vertebrates
• Regulates metabolism
• Any significant change in the sequence results in
  disease (diabetes)
• Insulin should be well conserved in all
  vertebrates
• Insulin is a homologous protein hormone

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WORKS CITED FOR BACKGROUND

• http//www.diabetes.org/home.jsp
• http//www.fda.gov/Diabetes/insulin.html2
• http//www.medbio.info/Horn/Time203-4/Insulin's2
  0Mechanism20of20Action.htm
• http//www.endocrineweb.com/diabetes/2insulin.html
  
• http//www.vivo.colostate.edu/hbooks/pathphys/endo
  crine/pancreas/insulin_phys.html
• http//www.medbio.info/Horn/PDF20files/insulin's
  20mechanism20of20action20new20october202006.p
  df
• http//www.abcam.com/index.html?pageconfigresourc
  erid10602pid7

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WORKS CITED FOR PHYLOGENY

• Madsen, O. D. (2007). Pancreas Phylogeny and
  Ontogeny in Relation to a "Pancreatic Stem Cell".
  Pubmed Central , 534-537.
• Rneteria, M. E., Gandi, N. S., Vineusa, P.,
  Helmerhorst, E., Mancera, R. L. (2008). A
  Comparative Study of the Bioinformatics Analysis
  of the Insulin Receptor Family Ectodomain Based
  on Phylogentic Information. Plos One , 1-15.
• Wilcox, G. (2005). A Review Article Insulin and
  Insulin Resistance. Clinical Biochemistry Review
  , 19-39.