Protein synthesis and disposal occur in highly regulated manner. In cells protein folding is assisted by special kind of proteins called as molecular chaperones and disturbances in protein quality control leads to deadly diseases

1. SyamprasadNP

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CONTENTS....
1. INTRODUCTION
2. PROTEIN STRUCTURE
3. FUNCTIONS OF PROTEINS
4. PROTEIN SYNTHESIS
5. FATE OF PROTEINS
7. REGULATION
8. CHAPERONE
9. PROTEIN QUALITY CONTROL
10. WHAT IS MISFOLDING
11. DISEASES
12. CYSTIC FIBROSIS
13. TYPE2 DM
14. TARGETS
15. CONCLUSION

3. INTRODUCTION
 Proteins are the most important macromolecules in living cells.
 Almost everything that occurs in the cell involves one or more
protein.
 Protein is a polypeptide.
 Amino acids are the building blocks of proteins.
 Proteins performs many functions in living organism.
 The functions of a protein depend on its amino acids sequence.
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4. FUNCTIONS OF PROTEINS
 According to function protiens are...
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Enzymes
Defense proteins
Regulatory proteins
Transport protein
Structural proteins
Contractile proteins
Lim, L. 'Mechanisms, Regulation And Special Functions Of Protein Synthesis In The Brain'. FEBS
Letters 97.2 (1979): 385.

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PROTEIN SYNTHESIS
DNA
TRASCRIPTION
mRNA
Pre mRNA
RNA Processing
TRANSLATION
NUCLEUS
RIBOSOME
FOLDING
FUNCTIONAL PROTEIN
RER
PROTEIN
Lim, L. 'Mechanisms, Regulation And Special Functions Of Protein Synthesis In The Brain'. FEBS
Letters 97.2 (1979): 385.

6.  Often translation is not sufficient to make a functional protein.
 Sometimes other molecules are also attached to the
polypeptides: sugars, lipids, phosphates, etc.
 Polypeptides fold spontaneously into their active
configuration.
 Some times the so formed proteins may misfolded (20%)
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FATE OF PROTEINS...
S. Walter Englander1*, Leland Mayne1 and Mallela M. G. Krishna1,2 Proteinfolding and misfolding :
mechanism and principles, Quarterly Reviews of Biophysics; 2008 Vol 40(4), 287-326

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What is folding???
Primary structure
Secondary structure
Tertiary structure
Hydrogen bond
Disulphide bond
S. Walter Englander1*, Leland Mayne1 and Mallela M. G. Krishna1,2 Proteinfolding and misfolding :
mechanism and principles, Quarterly Reviews of Biophysics; 2008 Vol 40(4), 287-326

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What is misfolding ???
Native protein
A. Hydrophobic parts will be assembled
inside and hydrophilic will be out side
B. α–helix will be much more than β–plated
sheet
Misfolded protein
A. More hydrophobic part will express
outside
B. α–helix will be less than β–plated sheet
S. Walter Englander1*, Leland Mayne1 and Mallela M. G. Krishna1,2 Proteinfolding and misfolding :
mechanism and principles, Quarterly Reviews of Biophysics; 2008 Vol 40(4), 287-326

9.  Cellular environment is very crowded.
 Possibilities for several interaction.
 Several possibilities for misfolding.
 Still protein folds in proper manner which is difficult to see in
invitro condition.
 In cells protein folding is assisted by special kind of proteins
called as molecular chaperones.
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REGULATION
Christopher J. Roberts, Therapeutic Protein Aggregation: Mechanisms, Design, and Control, Trends
Biotechnol. 2014 July ; 32(7): 372–380.

10.  “An older person who accompanies young people at a social
gathering to ensure proper behavior”
 Chaperons protect proteins from interfering interactions during
folding
 It help proteins in their folding process. By providing right
cellular environment.
 Unfold misfolded proteins.
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CHAPERONE......
Chaudhuri TK, Paul S. Protein-misfoldingdiseases and chaperone-based therapeutic
approaches. FEBS Journal 2010; 1331-1349.

11.  Selectevely bind to unfolded or misfolded proteins by
hydrophobic interactions
Chaperon
CHAPERONE......
ATP
ADP
Native protein
Unfolded protein
11Chaudhuri TK, Paul S. Protein-misfoldingdiseases and chaperone-based therapeutic
approaches. FEBS Journal 2010; 1331-1349.

12. CLASSIFICATION
 Heat shock protein 70/DnaK
 Heat shock protein 90,100,124
 Small heat shock proteins
 GroEL ,GroES
 Heat shock protein 40/DnaJ
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CHAPERONE......
Chaudhuri TK, Paul S. Protein-misfoldingdiseases and chaperone-based therapeutic
approaches. FEBS Journal 2010; 1331-1349.

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PROTEIN QUALITY CONTROL
Unfolded protein
Holding
chaperone
Folding
chaperone
Unfolding
chaperone
Ubiquitin
proteasome
Native protein
protein
aggregates
Misfolded
protein
Degraded
polypeptide
Unfavorable condition
Fibrils
Protein deficiency disorderProgression to disease or toxicity
R. J. Mayer, A. Ciechanover, M. Rechsteiner, Protein Degradation, Vol. 2: The Ubiquitin-Proteasome
System, KGaA, Weinheim ISBN, 2009: 3-527

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CAUSES FOR MISFOLDING
Mutation
Temperature
Altered cell chemistry
Metal ions
Protein Concentration
Crowding
Oxidative Stress
Misfolded
protein
S. Walter Englander1*, Leland Mayne1 and Mallela M. G. Krishna1,2 Proteinfolding and misfolding :
mechanism and principles, Quarterly Reviews of Biophysics; 2008 Vol 40(4), 287-326

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PROTEIN MISFOLDING DISEASES
Diseases Protein involved
Alzheimer‘s disease Amyloid-β,Tau
Parkinson disease α-Synuclein
Diabetes type 2 IAPP
Amylotrophic lateral sclerosis Superoxide dismutase
Cystic fibrosis CFTR
Sickle cell anemia Hemoglobin
Hungtington disease Huntingtin
Creutzfeldt-Jakob disease Prion protein
Amyloidosis Ten other proteins
Heart disease Desmin
Chaudhuri TK, Paul S. Protein-misfoldingdiseases and chaperone-based therapeutic
approaches. FEBS Journal 2010; 1331-1349.

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Defficiency of functional
protein
Forms insoluble
aggregates
PROTEIN MISFOLDING DISEASES
Cystic fibrosis, Marfan syndrome,
amylotrophic lateral sclerosis
Alzheimer’s,Parkinson’s, Type2
diabetes and many more
Chaudhuri TK, Paul S. Protein-misfoldingdiseases and chaperone-based therapeutic
approaches. FEBS Journal 2010; 1331-1349.

17.  In T2DM Amylin misfolding and Aggregation and death of β-
cells.
 Newer study-96% of T2DM patient having IAPP aggregates
 Translation of IAPP gene occurs In the absence of significant
ER stress, chaperones are able to properly fold IAPP.
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TYPE2 DIABETIC MELLITUS

18.  In the presence of significant ER stress
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TYPE2 DIABETIC MELLITUS
IAPP misfolding IAPP oligomers
chaperon
Islet amyloid
Ubiquitin-proteasome
apoptosis
Beta cell
death
Melvin R Hayden et.al Type 2 Diabetes Mellitus as a Conformational Disease, JOP. J Pancreas
(Online) 2005; 6(4):287-302.

19.  Desmin is a protein maintaining z-disc in myocardial muscle
filaments.
 Mutation in gene coding for desmin pN116s, pE114del.
 Chaperons anable to correctly fold mutated desmin.
 Misfolding and aggregation.
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HEART DISEASES

20.  misfolded proteins could easily interfere with either cell
metabolism or the inherent function of a cardiomyocyte.
 Leads to repeated cycles of uncontrolled contraction and
relaxation.
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HEART DISEASES
Xuejun Wang, Jeffrey Robbins; Heart Failure and Protein Quality Control, American Heart
Association.Inc, October 30, 2012.

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Upregulation of molecular chaperones.
Pharmacological chaperones
Inhibit protein aggregation
Upregulation of Ubiquitin proteasome system
TARGETS...

22.  Protein is an major component of our body and its synthesis
and disposal occur in highly regulated manner
 In cells protein folding is assisted by special kind of proteins
called as molecular chaperones.
 Disturbances in protein quality control leads to deadly diseases
 Unwinding the secrets of proteins can open a new path for
drug discovery
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SUMMARY

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