Re: "homology / similarity" of proteins

William Pitt (
Fri, 24 May 1996 12:45:14 +0100 (BST)

The following definition I found on the web confirms Clare's statement on
the subject.

sequence homology:
Strictly, refers to the situation where nucleic acid or protein sequences
are similar because they have a common evolutionary origin. Often used
loosely to indicate that sequences are very similar. Sequence similarity
is observable; homology is an hypothesis based on observation.

Dictionary of Cell Biology at

I have a question in a similar vein:

I heard Peer Bork (EMBL Germany) use the terms "paralogues" and
"orthologues" in a talk he gave in London in March. By these terms he ment
(I think) proteins with structural homology but different functions and
proteins with no structural homology but with the same function,
respectively. Has anyone else heard of these terms?