Attack of the "logues" - Terminology of logues..... (Apr/03/2005 )

Hi Forumers,

I am perplexed with the use of many words suffixed with logue. There has been a bit of contention within our lab as to when where and how to use it.

there is homologue (I think refers to similar genes within a species), then there is orthologue, and paralogue.

I use homologue for everything....but this is wrong.

Can someone clarify the meanings of homologue, paralogue and orthologue? Also are there any other "logues" I should be aware of?

Thanks in advance.

Nick

Hi!

homology: similarity or identity of a feature in structure or sequence. structures are homologues, if their (not accidentally) similarity or identity is derived by a shared genetic information... homology isn't reall sharply defined, it's more a vague criterium for similarity, often used in phylogenetic context.

orthologues: homologue genes in different organisms that have developed from an single ancestor gene in an ancetor organism, e.g. alpha-globulin genes in different mammals are orthologues.

paralogues: homologue genes in one single organism, that have developed by duplication from a single "ancestor" gene, e.g. alpha-, beta- and gamma- globulin genes in mammals are paralogues.

so, in a way you're right. if you use homologue all the time you're never really wrong, but could be more precice....

mike

cheers mike for the clarification!

much appreciated!

Nick

there's another -logue.. the analogue

Analogue refers to an entity (be it protein, tissue or organ) which has a comparable structure or function to something else, but is not evolutionary related at all.

hey,
that was wonderful, i was also confused about those logues
thanks