Anti-NPQ antibodies enable researchers to detect and measure the NPQ antigen in biological samples. This target is a reported synonym of the SPX gene, which encodes spexin hormone. This protein is known to function in the regulation of transcription, among other biological roles. The human version of NPQ has a canonical amino acid length of 116 residues and a protein mass of 13.3 kilodaltons. It is reported to be localized in the cytoplasmic vesicles and is secreted of cells. NPQ is a member of the Spexin protein family.