Anti-PER3 antibodies are used in the immunodetection of the protein period circadian regulator 3. In humans, the canonical protein has a reported length of 1201 amino acid residues and a mass of 131.9 kDa. Its subcellular localization is in the nucleus and cytoplasm. Alternative splicing is reported to yield 2 different isoforms for this protein. Among its functions, PER3 is involved with the regulation of transcription and protein stabilization. Post-translational modifications have been described, including ubiquitination and phosphorylation. Synonyms for this target antigen include GIG13, period circadian protein homolog 3, cell growth-inhibiting gene 13 protein, circadian clock protein PERIOD 3, period circadian clock 3, and FASPS3.