This family contains a number of bacterial SapC proteins approximately 250 residues long. In Campylobacter fetus, SapC forms part of a paracrystalline surface layer (S-layer) that confers serum resistance [1].

1: Campylobacter fetus surface layer proteins are transported by a type I secretion system. Thompson SA, Shedd OL, Ray KC, Beins MH, Jorgensen JP, Blaser MJ; J Bacteriol 1998;180:6450-6458. PMID:9851986