Members of this family are predominantly found in chondroitin ABC lyase I, and adopt a jelly-roll fold topology consisting of a two-layered bent beta-sheet sandwich with one short alpha-helix. The convex beta sheet is composed of five antiparallel strands, whilst the concave beta-sheet contains five antiparallel beta-strands with a loop between two consecutive strands folding back onto the concave surface. This domain is required for binding of the protein to long glycosaminoglycan chains [1].

1: Crystal structure of Proteus vulgaris chondroitin sulfate ABC lyase I at 1.9A resolution. Huang W, Lunin VV, Li Y, Suzuki S, Sugiura N, Miyazono H, Cygler M; J Mol Biol. 2003;328:623-634. PMID:12706721