This domain is found in BspA protein present in Streptococcus agalactiae. BspA is an antigen I/II family polypeptide that confers adhesion linked to pathogenesis in group B Streptococcus. This domain is referred to as the variable domain (BspA-V). BspA-V is responsible for binding to scavenger receptor gp340. BspA-V adopts a fold that is distinct from those of other AgI/II family polypeptide variable domains [1].

1: Structural and Functional Analysis of Cell Wall-anchored Polypeptide Adhesin BspA in Streptococcus agalactiae. Rego S, Heal TJ, Pidwill GR, Till M, Robson A, Lamont RJ, Sessions RB, Jenkinson HF, Race PR, Nobbs AH; J Biol Chem. 2016;291:15985-16000. PMID:27311712