<p>The osteonectin like domain, of unknown function, is found in extracellular proteins strongly expressed in tissues undergoing morphogenesis. It is a 240 amino acids domain, highly conserved, localized in the C-terminal part of the protein [<cite idref="PUB00001526"/>].</p><p>This domain has a N-terminal section of about 90 residues that contains 11 conserved cysteines, a central section that is probably in an alpha-helical conformation, and a C-terminal section that contains two EF-hand type calcium-binding regions [<cite idref="PUB00003931"/>] and three conserved cysteines. This topology is schematically represented below.</p><pre> +----+ | | xCxCxCxxCCxCxxxCxxCxCxxxxxCxCxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx(Ca)xCxxC(Ca)Cxx</pre>C: conserved cysteines involved in disulphide bonds.Ca: EF-hand region see(<db_xref db="INTERPRO" dbkey="IPR002048"/>). Osteonectin-like, conserved site