<p> Proteins containing a galactose-binding domain-like fold can be found in several different protein families, in both eukaryotes and prokaryotes. The common function of these domains is to bind to specific ligands, such as cell-surface-attached carbohydrate substrates for galactose oxidase and sialidase [<cite idref="PUB00004093"/>], phospholipids on the outer side of the mammalian cell membrane for coagulation factor Va [<cite idref="PUB00010664"/>], membrane-anchored ephrin for the Eph family of receptor tyrosine kinases [<cite idref="PUB00010665"/>], and a complex of broken single-stranded DNA and DNA polymerase beta for XRCC1 [<cite idref="PUB00005865"/>].</p><p> The structure of the galactose-binding domain-like members consists of a beta-sandwich, in which the strands making up the sheets exhibit a jellyroll fold. There is a high degree of similarity in the beta-sandwich and in the loops between different family members, despite an often low level of sequence similarity.</p>