Anti-HEG1 antibodies are used in the immunodetection of the protein heart development protein with EGF like domains 1. In humans, the canonical protein has a reported length of 1381 amino acid residues and a mass of 147.5 kDa. Its subcellular localization is in the cell membrane and is also secreted. Alternative splicing is reported to yield 2 different isoforms for this protein. HEG1 is a known receptor component of the CCM signaling pathway which is a crucial regulator of heart and vessel formation and integrity. Post-translational modifications have been described, including glycosylation. Synonyms for this target antigen include protein HEG homolog 1 and heart of glass.