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Pseudogenes

Keith Robison robison at nucleus.harvard.edu
Sun Sep 10 20:43:29 EST 1995


Ram Samudrala (ram at mbisgi.umd.edu) wrote:
: Keith Robison (robison at mito.harvard.edu) wrote:

: >Ram Samudrala (ram at mbisgi.umd.edu) wrote:
: >: Paul Linehan (linehan at ceph.cephb.fr) wrote:

: >: >They can of course be ancient or recent. They normally arise from
: >: >functional genes and not vice-versa (at least to my knowledge).

: >: If a functional gene arose from a pseudogene, it would not be
: >: classified as a pseudogene.

: >It's not clear that this is true -- a pseudogene (or portions
: >of it) might be resurrected -- much in the way a wrecked car
: >can still provide useful parts.  A pseudogene which has undergone
: >only a few mutational hits might be resurrected in part by
: >combining with another gene.

: I was just pointing out what I thought was an issue of definition.  It
: is not clear to me what Paul means by "vice-versa", but I don't see
: the meaning of it.  When you have a functional gene, regardless of
: where it arose from, it will not be classified as a pseudogene.  It
: might be true that functional genes can arise from pseudogenes and
: pseudogenes can arise from functional genes, but if the former
: happens, I don't see the meaning in classifying it a pseudogene.

: In your example, Keith, if a pseudogene is indeed resurrected, it
: would be "functional" and therefore, there'd be no reason to call it
: "pseudo".

: It's just that the "vice-versa" struck me funny.  

Like you said -- it's a definitional issue, and I don't think
we really have much disagreement.  However, I would argue (mildly)
that a pseudogene is a gene which is not under selection --
and a gene could go through a period of no selection and then
acquire a function and be under selection.

It's definitely a definitional problem -- how do you know a 
pseudogene is a pseudogene?  I don't think there's a simple
answer.


Keith Robison
Harvard University
Department of Cellular and Developmental Biology
Department of Genetics / HHMI

robison at mito.harvard.edu 





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