Members of this family adopt a structure consisting of seven/eight-strand antiparallel beta-sheets, in a Greek-key topology, similar to the immunoglobulin beta-sandwich fold. They act as cell wall anchors, where they interact with the S-layer present in the cell wall of Gram-positive bacteria by hydrophobic interactions. In glucodextranase, Domain B is buried in the S-layer, and a flexible linker located between domain B and the catalytic unit confers motion to the catalytic unit, which is capable of efficient hydrolysis of the substrates located close to the cell surface [1].

1: Structural insights into substrate specificity and function of glucodextranase. Mizuno M, Tonozuka T, Suzuki S, Uotsu-Tomita R, Kamitori S, Nishikawa A, Sakano Y; J Biol Chem. 2004;279:10575-10583. PMID:14660574