The protein fold of the hyaluronate-binding proteoglycan tandem repeat domain of link protein, aggrecan and CD44 is similar to that of the C-type lectin superfamily.

Link protein and aggrecan of the extracellular matrix each contain two proteoglycan tandem repeat (PTR) domains that interact with hyaluronate. Consensus secondary structure predictions for 59 PTR sequences and 129 C-type lectin sequences give similar patterns of two alpha-helices and up to seven beta-strands. Protein fold recognition analyses show that the 59 PTR sequences are highly compatible with the C-type lectin crystal structure. The predicted fold consists of a conserved motif formed from an antiparallel beta-sheet flanked by two alpha-helices, the motif being attached to two distinct types of beta-sheet region in the two superfamilies. Arg9 or Lys11 on an exposed loop and up to three other Arg residues in the beta-sheet region are conserved and may form part of a hyaluronate binding site.