This is a family of spirochete major outer sheath protein C-terminal regions. These proteins are present on the bacterial cell surface. In T. denticola the major outer sheath protein (Msp) binds immobilised laminin and fibronectin supporting the hypothesis that Msp mediates the extracellular matrix binding activity of T. denticola [1]. This domain forms an amphipathic beta rich structure with channel forming activity [2].

1: Conservation of msp, the gene encoding the major outer membrane protein of oral Treponema spp. Fenno JC, Wong GW, Hannam PM, Muller KH, Leung WK, McBride BC; J Bacteriol 1997;179:1082-1089. PMID:9023187

2: The major outer sheath protein (Msp) of Treponema denticola has a bipartite domain architecture and exists as periplasmic and outer membrane-spanning conformers. Anand A, Luthra A, Edmond ME, Ledoyt M, Caimano MJ, Radolf JD; J Bacteriol. 2013;195:2060-2071. PMID:23457251