[BiO BB] protein identity

[Philipp Pagel]

		Hi!

On Mon, Oct 22, 2001 at 01:42:08PM -0700, nabula easter wrote:
>   When two proteins are 98-99% identical, what is the
> relationship associated between them. 
>  Can we call those proteins as very close homologues !
> or that 2% difference between then is due to sequence
> errors at Nucleic acid level.
> At nucleic acid level they would be 94% identical and
> we can say a sequnce error!


That depends on how reliable your sequence is. If your sequence data is 
reliable you have a close homologue. What exactly that means depends on the
source of the DNA and functional data:

	- In the same species you might be looking at different isoforms - maybe 
	  with functional differences.
	- If it's from different species it is likely that they are functionally 
	  the same thing.
  - The proteins might also have significantly different functions although 
    you would expect less identity.

So they could be orthologs, paralogs, isoforms or just sequencing errors. Was 
this a hypothetical question or are you talking about something you are working 
on right now? If it's a real-world question you may want to tell us where the
sequence data came from and we can narrow it down some more.


cu and hope it helps

 	Philipp

-- 
Dr. Philipp Pagel
Department of Cellular and Molecular Physiology         phone: (203) 785-6835	
SHM, B117                                               fax:   (203) 785-4951
Yale University
333 Cedar ST
New Haven, CT 06520
USA