Head domain of virus receptor-binding proteins (RBP)
Virus receptor-binding proteins (RBPs) are found in lactococcal bacteriophages, as well as in adenoviruses and reoviruses, which invade mammalian cells. Lactococcus lactis is widely used in dairy fermentations and infection of L. lactis by phages greatly impairs the fermentation process. Adenovirus typically infects respiratory tracts with symptoms ranging from the common cold to pneumonia. Onset of viral infections begin with the recognition of host cells through the receptor-binding protein complex located at the distal part of the virion. The RBP has three domains: the N- terminal shoulders domain, the interlaced neck domain, and the C-terminal head domain. Phages recognize their host through an interaction between the RBP head (RBP-H) domain and saccharidic receptors at the host cell surface. Adenovirus recognizes the membrane cofactor protein, CD46, as a cellular receptor.