Anti-GPI antibodies are used in the immunodetection of the protein glucose-6-phosphate isomerase. In humans, the canonical protein has a reported length of 558 amino acid residues and a mass of 63.1 kDa. Its subcellular localization is in the cytoplasm and is also secreted. Alternative splicing is reported to yield 2 different isoforms for this protein. A member of the GPI protein family, it is known to be involved with carbohydrate metabolism and homeostasis and in utero embryonic development. Post-translational modifications have been described, including phosphorylation. Synonyms for this target antigen include GNPI, NLK, PGI, PHI, SA-36, SA36, autocrine motility factor, and AMF.