pfam04092: SAG (This model is not part of the current CDD release)
SRS domain
Toxoplasma gondii is a persistent protozoan parasite capable of infecting almost any warm-blooded vertebrate. The surface of Toxoplasma is coated with a family of developmentally regulated glycosylphosphatidylinositol (GPI)-linked proteins (SRSs), of which SAG1 is the prototypic member. SRS proteins mediate attachment to host cells and interface with the host immune response to regulate the virulence of the parasite. SAG1 is composed of two disulphide linked SRS domains. These have 6 cysteines that form 1-6,2-5 and 3-4 pairings. The structure of the immunodominant SAG1 antigen reveals a homodimeric configuration. The SRS domain is found in a single copy in the SAG2 proteins. This family of surface antigens are found in other apicomplexans.
Jiyao W et al.(2023). "The conserved domain database in 2023.",