This family, the N-terminal segment, is the most variable part of the variant surface antigen family of Plasmodium falciparum, the erythrocyte membrane protein-1 (PfEMP1) proteins. PfEMP1 is an important target for protective immunity and is implicated in the pathology of malaria through its ability to adhere to host endothelial receptors. A structural and functional study of the N-terminal domain of PfEMP1 from the VarO variant comprising the N-terminal segment (NTS) and the first DBL domain (DBL1alpha1), shows this region is directly implicated in rosetting. NTS, previously thought to be a structurally independent component of PfEMP1, forms an integral part of the DBL1alpha domain that is found to be the important heparin-binding site. This family is closely associated with PFEMP, pfam03011, and Duffy_binding, pfam05424.