This family consists of the p50 and variable adherence-associated antigen (Vaa) adhesins from Mycoplasma hominis. M. hominis is a mycoplasma associated with human urogenital diseases, pneumonia, and septic arthritis [1]. An adhesin is a cell surface molecule that mediates adhesion to other cells or to the surrounding surface or substrate. The Vaa antigen is a 50-kDa surface lipoprotein that has four tandem repetitive DNA sequences encoding a periodic peptide structure, and is highly immunogenic in the human host [1]. p50 is also a 50-kDa lipoprotein, having three repeats A,B and C, that may be a tetramer of 191-kDa in its native environment [2].

1: Molecular basis of size and antigenic variation of a Mycoplasma hominis adhesin encoded by divergent vaa genes. Zhang Q, Wise KS; Infect Immun 1996;64:2737-2744. PMID:8698503

2: Repetitive elements of the Mycoplasma hominis adhesin p50 can be differentiated by monoclonal antibodies. Henrich B, Kitzerow A, Feldmann RC, Schaal H, Hadding U; Infect Immun 1996;64:4027-4034. PMID:8926064