EncD is a cargo protein of a type 1 encapsulin nanocompartment. It may help nucleate Fe atoms in the interior of the encapsulin nanocompartment. and is present in about 47 copies/encapsulin nanocompartment (McHugh et al. 2014). The encapsulin and a cargo construct (an encB-encC-encD fusion) can be overexpressed in E. coli and in human HEK293T cells. In HEK293T in the presence of 0.5 M ferrous ammonium sulfate (Sigmund et al. 2019).