[BiO BB] orthologs vs in-paralogs

hz5 at njit.edu hz5 at njit.edu
Fri Sep 5 08:31:05 EDT 2003


This is a good question, please drop me a note if you guys get some answers.

For all I know, besides the homolog part, the key difference is that ortholog 
is same function in different species, while paralog is different function in 
same species.

Please keep me posted!
Thanks!
haibo
//cheers

Quoting Dan Bolser <dmb at mrc-dunn.cam.ac.uk>:

> Phil Luo said:
> > Dear all,
> >
> > As we know ,there are two kinds of homolog, ortholog and paralog.
> Genes in two
> > species that have directly evolved from a single gene in the last
> common ancestor
> > are called orthologs. A set of homologous genes that have diverged
> from each other
> > as a consequence of genetic duplication are called paralogs. Sometime
> those
> > paralogs which arose from a duplication after the speciation event are
> called
> > in-paralogs.
> >
> > My question is how to distinguish the in-paralogs from orthologs.
> Which one is
> > supposed to be more similar, in-paralogs or orthologs?
> 
> Hi,
> Good question! Maby someone on the sequence searching mailing list can
> help answer,
> 
> http://bioinformatics.org/mailman/listinfo/ssml-general
> 
> 
> I know of some work trying to uncover 'lineage specific gene expansion'
> by Eugene
> Koonin (sp?) at the NCBI. That sounds a bit like the in-paralogues you
> describe.
> Also he and coworkers define an algorithm for predicting orthologous
> pairs, simply
> 'best hits' between genome 1 and 2.
> 
> Although I understand the definition of orthology and paralogy, I find
> the concepts
> a bit confusing. I don't know what information you loose by simply
> talking about
> gene families, and ignoring the within / between genome distinction.
> 
> At some level does't ortholog mean 'same gene', and paralog mean
> 'copy'?
> 
> Cheers,
> 
> > Best regards,
> > Phil
> >
> >
> > ---------------------------------
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> 
> 
> 
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=========================================================
Haibo Zhang, PhD student
Computational Biology, NJIT & Rutgers University
Center for Applied Genomics, PHRI
http://afs13.njit.edu/~hz5



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