Endosperm-specific cysteine-rich protein that acts downstream of BHLH95/ZOU to modify the interface between embryo and endosperm and mediate the separation of these two tissues during seed development. Necessary for the biogenesis of the embryo sheath, an extracuticular endosperm-derived structure at the surface of the embryo. Required for the separation of embryo and endosperm, and for normal progression of the embryo through the endosperm tissue. Required for the formation of a normal embryonic cuticle. Specifically expressed in seed endosperm at torpedo stage embryo development. Increased embryonic cuticule permeability. Altered cotyledon development. Cup-shaped cotyledons. Belongs to the STIG1 family. Truncated N-terminus.