  Protein complexes conserved across species indicate processes that are core
to cellular machinery (e.g. cell-cycle or DNA damage-repair complexes conserved
across human and yeast). While numerous computational methods have been devised
to identify complexes from the protein interaction (PPI) networks of individual
species, these are severely limited by noise and errors (false positives) in
currently available datasets. Our analysis using human and yeast PPI networks
revealed that these methods missed several important complexes including those
conserved between the two species (e.g. the MLH1-MSH2-PMS2-PCNA mismatch-repair
complex). Here, we note that much of the functionalities of yeast complexes
have been conserved in human complexes not only through sequence conservation
of proteins but also of critical functional domains. Therefore, integrating
information of domain conservation might throw further light on conservation
patterns between yeast and human complexes.
