Identification of Polypeptides Constituting Lactophorin by Monoclonal Antibody to Bovine Milk Lactophorin

Abstract

A monoclonal antibody to lactophorin (LP) was prepared by creating hybridoma from mouse myeloma cells and spleen cells from mice immunized with PAS-4 concentrated fraction from bovine milk fat globule membrane. The prepared antibody recognized a polypeptide moiety of LP27, the major component constituting LP, but not a carbohydrate moiety. Immunoblot analysis showed that all polypeptides (LP17, LP20, LP27, LP40, and LP50) constituting LP were recognized by the antibody. The identities of LP20, LP40, and LP50 were verified by N-terminal and internal amino acid sequencing. LP20 contains hydrolysate of LP27 besides LP27 without the O-glycosyl sugar chain. These results suggest that LP40 and LP50 are homo- or heterodimers of LP20 and LP27. This is the first report to the effect that LP was constructed from several forms of polypeptides, derived from LP27.