This domain is found in eukaryotes, and is approximately 60 amino acids in length. There is a single completely conserved residue C that may be functionally important. This is a calcium binding domain from the fungal protein CBP (calcium binding protein). This protein is a virulence factor with unknown virulence mechanisms. CBP complexes as a highly intertwined homodimer. Each monomer is comprised of four alpha helices which adopt the saposin fold, characteristic of a protein family that binds to membranes and lipids.

1: NMR structure of a fungal virulence factor reveals structural homology with mammalian saposin B. Beck MR, Dekoster GT, Cistola DP, Goldman WE; Mol Microbiol. 2009;72:344-353. PMID:19298372