This is a helical coiled-coil domain found in reticulocyte-binding protein homolog 5 (RH5), a Plasmodium falciparum protein essential for erythrocyte invasion [1].

1: Crystal structure of PfRh5, an essential P. falciparum ligand for invasion of human erythrocytes. Chen L, Xu Y, Healer J, Thompson JK, Smith BJ, Lawrence MC, Cowman AF; Elife. 2014; [Epub ahead of print] PMID:25296023