This alignment represents the conserved core region of ~90 residue repeat found in several haemagglutinins and other cell surface proteins. Sequence similarities to (Pfam:PF02494) and (Pfam:PF00801) suggest an Ig-like fold (personal obs:C. Yeats). So this family may be similar in function to the (Pfam:PF02639) and (Pfam:PF02638) domains. This domain is also found in the WisP family of proteins of Tropheryma whipplei ([1]).

1: Sequencing and analysis of the genome of the Whipple's disease bacterium Tropheryma whipplei. Bentley SD, Maiwald M, Murphy LD, Pallen MJ, Yeats CA, Dover LG, Norbertczak HT, Besra GS, Quail MA, Harris DE, von Herbay A, Goble A, Rutter S, Squares R, Squares S, Barrell BG, Parkhill J, Relman DA; Lancet 2003;361:637-644. PMID:12606174