Members of this family contain multiple BNR (bacterial neuraminidase repeat) repeats or Asp-boxes. The repeats are short, however the repeats are never found closer than 40 residues together suggesting that the repeat is structurally longer. These repeats are found in many glycosyl hydrolases as well as other extracellular proteins of unknown function.

1: Conserved sequences in bacterial and viral sialidases. Roggentin P, Rothe B, Kaper JB, Galen J, Lawrisuk L, Vimr ER, Schauer R; Glycoconj J 1989;6:349-353. PMID:2562507

2: Sialidase-like Asp-boxes: sequence-similar structures within different protein folds. Copley RR, Russell RB, Ponting CP; Protein Sci 2001;10:285-292. PMID:11266614