Anti-DDDD antibodies are protein reagents that detect specific antigens. The DDDD antigen is another term for the human protein single-pass membrane protein with aspartate rich tail 1, encoded by the SMDT1 gene. The protein is known to be an important regulatory subunit of the mitochondrial calcium uniporter complex (uniplex), a complex that mediates calcium uptake into mitochondria. Canonically, it has an amino acid length of 107 residues and a mass of 11.4 kilodaltons. Its subcellular localization is in the mitochondria. The DDDD protein is a member of the SMDT1/EMRE protein family.