FND-PPI-Physical vs genetic
Physical- vs. Genetic Interactions
(The fundamental difference between physical and “genetic” interactions. Topology of pathways.)
Abstract:
This unit discusses how "genetic interactions" are measured and can be used to infer pathway topologies.
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Prerequisites:
This unit builds on material covered in the following prerequisite units:
Contents
Genetic interactions are very different from physicl interactions. Here the word interaction is used in an entirely different sense: it is not synonymous with contact it is synonymous with influence. In fact, most proteins that display genetic interactions would not be expected to interact physically as well. (Why? Think.) It is important not to mix up the two.
To understand what genetic interactions imply, think of the following analogy. If I were to break the wrist of my right arm, my survival would probably not be affected. My left arm would provide sufficient redundancy for most tasks. What about breaking the right index finger, or spraining the elbow as well? Painful, but functionally not much worse than breaking the wrist alone. What about indigestion, bunyons, cancer, or Alzheimers in addition to the fracture? Annoying, but really not significantly more so with or without a broken wrist. What about a broken left wrist? That would be bad. Losing the function of both hands is much, much worse than losing the function of only one hand. This is the kind of functional ordering that genetic interactions achieve: if two genes are active in the same system (like the right wrist and index finger) they will not display genetic interaction. The pathway is blocked and it matters little whether it is blocked in one or two points. If two genes work in completely different systems, they will also not show genetic interactions (like a fracture, combined with indigestion). Only if two genes affect parallel, mutually redundant pathways (left and right arm) will their joint deletion cause a critical situation for the affected organism. If the organism dies, we call this a synthetic lethal effect.
Genetic interactions can be observed in high-throughput experiments that systematically explore all pairs of gene-deletions in an organism, and the results provide insight how pathways can be topologically ordered according to shared objectives!
Task:
Self-evaluation
Notes
Further reading, links and resources
If in doubt, ask! If anything about this learning unit is not clear to you, do not proceed blindly but ask for clarification. Post your question on the course mailing list: others are likely to have similar problems. Or send an email to your instructor.
About ...
Author:
- Boris Steipe <boris.steipe@utoronto.ca>
Created:
- 2017-08-05
Modified:
- 2017-11-09
Version:
- 1.0
Version history:
- 1.0 First live
- 0.1 First stub
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