In article <199604180052.VAA23810 at bud.peinet.pe.ca>, eswright at NS.SYMPATICO.CA (Edwin Stephen Wright) writes:
> A review of protein sequence databases reveal a number of identical cytochrome c
> sequences among different species, some within the same taxonomic genus, family or
> order, but at least one example within the mammalian class of identical cytochrome c
> sequences between two species of different taxonomic orders. The following are three
> examples of identical cytochrome c sequences:
>> 1) PIR1:CCRT (Rat) and PIR1:CCRT (Mouse) --- (same taxonomic family, i.e. Muridae -
> Old World Rats and Mice)
>> 2) PIR1:CCRS (Eastern Diamondblack Rattlesnake) and PIR1:CCRSW (Western Rattlesnake)
> --- (same taxonomic genus, i.e. Crotalus)
>> 3) PIR1:CCWHC (California Gray Whale) and PIR1:CCCM (Arabian Camel) and
> PIR1:CCGW (Guanaco) --- (two different taxonomic orders, i.e. Mysticeta (Whale),
> and Artiodactyls (Camel and Guanaco))
>> Does anyone know if any conclusions have been drawn from data pertaining to
> intra-species cytochrome c identities, i.e. can one infer that cytochrome c function
> is essentially identical at least among species within the same taxonomic phylum?
>> Regards,
>> Edwin Wright
>
Hi Edwin:
cytochrome c just "goes" very slowly; it has a very slow clock. It is by no
means the only protein that will be identical at the amino acid level
between rats and mice etc. The one example above of sequnecs from two
different orders (cetacea and artiodactyls) is a case where those two orders
are particularly "close" anyway. You cannot infer much except that it
has a slow clock which is normally considerd to imply that there is great
constraint on changing any of its amino acids.
Des Higgins
>>
