Anti-FSA antibodies enable researchers to detect and measure the FSA antigen in biological samples. This target is a reported synonym of the BLTP1 gene, which encodes bridge-like lipid transfer protein family member 1. The human version of FSA has a canonical amino acid length of 5005 residues and a protein mass of 555.5 kilodaltons, although 6 isoforms have been identified. It is reported to be localized in the mitochondria, ER, and cell membrane of cells and notably expressed in many tissues, such as the bronchus, tonsil, and appendix.