This family consists of several Neisseria species specific OpcA outer membrane proteins. Opc (formerly called 5C) is one of the major outer membrane proteins and has been shown to play an important role in meningococcal adhesion and invasion of both epithelial and endothelial cells [1].

1: Identification of opcA gene in Neisseria polysaccharea: interspecies diversity of Opc protein family. Zhu P, Klutch MJ, Derrick JP, Prince SM, Tsang RS, Tsai CM; Gene 2003;307:31-40. PMID:12706886