Probably part of an ABC transporter complex involved in arginine transport. Binds arginine. Interacts with host epithelial cells, suggesting a role in host-cell adhesion during infection. Was identified as a potential vaccine component. In vitro, induces antibodies capable of neutralizing the infectivity of C.pneumoniae. This protein, although well conserved among chlamydial species, shows species-specific immunogenicity. Belongs to the bacterial solute-binding protein 3 family. Truncated N-terminus.