Reticulocyte binding protein homologs
Reticulocyte binding protein homologs are a superfamily of proteins found in Plasmodium responsible for cell invasion. Together with the family of erythrocyte binding-like proteins they make up the two families of invasion proteins universal to Plasmodium. The two families function cooperatively.
This family is named after the reticulocyte binding proteins in P. vivax, a parasite that only infects reticulocytes expressing the Duffy antigen. Homologs have since been identified in P. yoelii and P. reichenowi. A P. falciparum protein complex called PfRH5-PfCyRPA-PfRipr is known to bind basigin, has its structure known, and is a potential vaccine target. PfRH4 is known to bind complement receptor 1.
RHs do not express any significant sequence feature for specific domains, except for a set of transmembrane helices at the C-terminal. From experimentation on partial proteins, RHs are known to contain enterocyte-binding and nucleotide-sensing domains that may partially overlap. The structure of the EBD has been experimentally observed in 2011 by small angle X-ray scattering. A much better crystal structure for an N-terminal receptor-binding domain was published in 2014.
