Anti-sestrin 1 antibodies are used in the immunodetection of the protein encoded by the SESN1 gene. In humans, the canonical protein has a reported length of 492 amino acid residues and a mass of 56.6 kDa. Its subcellular localization is in the nucleus and cytoplasm. Alternative splicing is reported to yield 3 different isoforms for this protein. It is widely expressed across many tissue types. A member of the Sestrin protein family, it is known to function as a intracellular leucine sensor that negatively regulates the TORC1 signaling pathway through the GATOR complex. Other names for this target antigen include SEST1, p53 activated gene 26, p53 regulated PA26 nuclear protein, and PA26.