Gamma-secretase activating protein, or, GSAP, is a human gene. Other names include: Gamma-secretase-activating protein; Protein pigeon homolog; PION. The encoded protein has an amino acid length of 854 and a mass of 97.8 kDa. Other isoforms may exist. Gamma-secretase activating protein is a member of the GSAP family. This gene shares homology with other species, including: Mouse, Rat, Zebrafish.