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gene redundancy?

Genetics as it applies to evolution, molecular biology, and medical aspects.

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gene redundancy?

Postby chatty » Tue Apr 05, 2011 7:30 pm

I am having a hard time understanding this concept.

If I have 3 genes (ABC1, ABC2 and DEF1) lets say.

If ABC1 and ABC2 are redundant, what would it mean if DEF1 is redundant with them?

Does that mean that if ABC1 is knocked out, ABC2 will still function and the gene functionality is the same.

(1) So, the same would apply if either ABC2 or DEF1 are knocked out, right?

(2) If all three are knocked-out, then what happens? Does that mean that THEN the gene functionality ceases?

(3) If two of the genes are knocked out, then the third still allows the gene to function?

Am I getting this, or am I way off?
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Postby JackBean » Tue Apr 05, 2011 9:11 pm

I think you're on the right way.
If you have three proteins, which are redundant, they should do the same at the same time and at the same stage. However, usually they are only partially redundant, e.g. ine isoform is expressed in brain, spleen and heart, second in gastrointestinal tract, muscles, spleen and heart and third in brain and muscles. Thus, if you knock-out first, in brain is still the 3rd isoform and in spleen and heart is still the 2nd isoform, so you should not see much differences. Etc. etc.
Furthermore, they usually also differ in properties (e.g. preference for substrate, speed of reactions, Michaelis constant etc.), so there will be some difference anyway
(at east, there will be less of the enzyme, rigth?)
http://www.biolib.cz/en/main/

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Postby chatty » Tue Apr 05, 2011 10:24 pm

So, as long as 1 of the 3 genes is 'functioning' then the 3rd gene will prevent you from seeing any difference, right? As you said, there may a slight change but really because of redundancy the 3rd gene will keep the organ functioning (as in your example).

Correct?
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Postby JackBean » Wed Apr 06, 2011 5:18 am

that depends on the degree of redundancy. If they were really expressed in the same organs and have the same properties (if there was any duplication in the near past), than yes, you shouldn't see much difference (although there will be less of enzyme). However, that is not often the truth. For example, in Arabidospsis there are three cytokinin receptors and when you make single knock-outs, you do not see much difference from WT, as the other two receptors are still enough and complementary, but when you double knock-outs, the plants are much smaller and have other difficulties, because the remaining receptor is too much specialized and is not enough to complement the other two receptors ;)
http://www.biolib.cz/en/main/

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