Introduction. Types of Protein – Protein Interaction. Methods to investigate Protein – Protein Interaction. Protein – Protein Interaction modulated by Chemical energy. Two Hybrid Screening. Overview of Protein – Protein Interaction analysis. Biological effect of Protein – Protein interaction. Conclusion. Reference.

1. PROTEIN- PROTEIN INTERACTION.
By
KAUSHAL KUMAR SAHU
Assistant Professor (Ad Hoc)
Department of Biotechnology
Govt. Digvijay Autonomous P. G. College
Raj-Nandgaon ( C. G. )

2. SYNOPSIS
1. Introduction.
2. Types of Protein – Protein Interaction.
3. Methods to investigate Protein – Protein Interaction.
4. Protein – Protein Interaction modulated by Chemical energy.
5. Two Hybrid Screening.
6. Overview of Protein – Protein Interaction analysis.
7. Biological effect of Protein – Protein interaction.
8. Conclusion.
9. Reference.

3. Introduction.
• Protein–protein interactions occur when two or more proteins bind together,
often to carry out their biological function.
• Many of the most important molecular processes in the cell such as DNA
replication are carried out by large molecular machines that are built from a
large number of protein components organized by their protein–protein
interactions.
• Proteins might interact for a long time to form part of a protein complex, a
protein may be carrying another protein (for example,
from cytoplasm to nucleus or vice versa in the case of the nuclear
pore importins), or a protein may interact briefly with another protein just to
modify it (for example, a protein kinase will add a phosphate to a target
protein).

4. Types of protein-protein interactions
• Protein interactions are fundamentally characterized as stable or
transient, and both types of interactions can be either strong or weak.
• Stable interactions are those associated with proteins that are purified as
multi-subunit complexes, and the subunits of these complexes can be
identical or different.
• Hemoglobin and core RNA polymerase are examples of multi-subunit
interactions that form stable complexes.
• Transient interactions are expected to control the majority of cellular
processes. As the name implies, transient interactions are temporary in
nature and typically require a set of conditions that promote the
interaction, such as phosphorylation, conformational changes or
localization to discrete areas of the cell.

5. Methods to investigate protein–protein
interactions
• As protein–protein interactions are so important there are a
multitude of methods to detect them.
• High-throughput detection methods include yeast two-
hybrid screening and affinity capture mass spectrometry.

6. Protein - Protein interaction modulated
by chemical energy.

7. The Major Proteins of Muscle Are Myosin
and Actin.

8. Myosin Thick Filaments Slide along
Actin Thin Filaments

9. Two-hybrid screening

10. Three-hybrid

11. Overview of Protein-Protein Interaction
Analysis.
• Common methods to analyze the various types of protein interactions
• Method
Protein-Protein Interactions
• Co-Immunoprecipitation (co-IP)
Stable or strong
• Pull-Down Assay
Stable or strong
• Crosslinking Protein Interaction Analysis
Transient or weak
• Label Transfer Protein Interaction Analysis
Transient or weak
• Far-Western Blot Analysis
Moderately stable

12. Biological effects of protein-protein
interactions.
 Alter the kinetic properties of enzymes, which may be the result of subtle
changes in substrate binding or allosteric effects
 Allow for substrate channeling by moving a substrate between domains
or subunits, resulting ultimately in an intended end product
 Create a new binding site, typically for small effector molecules
 Inactivate or destroy a protein
 Change the specificity of a protein for its substrate through the interaction
with different binding partners; e.g., demonstrate a new function that
neither protein can exhibit alone.

13. Conclusion
 Many of the most important molecular processes in the cell such
as DNA replication are carried out by large molecular machines
that are built from a large number of protein components
organised by their protein–protein interactions.
 Proteins bind to each other through a combination of hydrophobic
bonding, van der Waals forces, and salt bridges at specific binding
domains on each protein.
 Proteins control all biological systems in a cell, and while many
proteins perform their functions independently, the vast majority
of proteins interact with others for proper biological activity.

14. Reference.
 Lehninger Principles of Biochemistry – Michael M. Cox ,
David L. Nelson. Fifth edition.
 Net source.