<p>This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.</p> <p>Conserved hypothetical proteins, i.e. conserved proteins whose functions are still unknown,
pose a challenge not just to functional genomics but also to general biology. For many
conserved proteins, computational analysis provides only a general prediction of
biochemical function; their exact biological functions have to be established through
direct experimentation. In the few cases when this has been accomplished, the results were
remarkable, revealing the deoxyxylulose pathway and a new essential enzyme, the ITP
pyrophosphatase. Comparative genome analysis is also instrumental in illuminating
unsolved problems in biology, e.g. the mechanism of FtsZ-independent cell division in
<italic>Chlamydia, Ureaplasma</italic> and <italic>Aeropyrum</italic> or the role of uncharacterized conserved domains
in signal transduction.</p>
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Comp Funct Genomics. 2001 Feb; 2(1):14-18