Onchocerca volvulus Calcium Binding Protein (EF12)
entry list
alignment
A 542 residue protein of unknown function has been isolated from the
nematode, Onchocerca volvulus, as well as its close homolog of 482
residues from Caenorhabditis elegans [50]. It has twelve EF-hands,
eleven of which conform well to the consensus of figure 1 and appear to
bind calcium. The fourth EF-hand is highly diverged; however, of all
EF-hand domains it most closely resembles EF12 #2. The eleven
interdomain spacings are all six residues; this pattern strengthens the
interpretation that the 41 (6 + 29 + 6) residues between EF-hands 3 and
5 harbors an aberrant domain. In a dendrogram the six ODD domains
cluster together and are congruent with the six EVEN domains. Further
domains 1(2) & 7(8), 3(4) & 9(10), and 5(6) & 11(12) most closely
resemble one another, reflecting four cycles of gene duplication and
fusion. It is surely significant that the O. volvulus and the C.
elegans proteins align well, with no deletions, over the 414 residues
(12 * 29 + 11 * 6) residues encompassing the twelve EF- hands but show
many deletions in the N-terminal and C-terminal domains. The six pairs
of EF-hands might be arranged helically and undergo a cooperative
change in conformation upon binding calcium.