Anti-nuclear factor I C antibodies are used in the immunodetection of the protein encoded by the NFIC gene. In humans, the canonical protein has a reported length of 508 amino acid residues and a mass of 55.7 kDa. Its subcellular localization is in the nucleus. Alternative splicing is reported to yield 6 different isoforms for this protein. A member of the CTF/NF-I protein family, it is known to recognize and bind the palindromic sequence 5'-TTGGCNNNNNGCCAA-3' present in viral and cellular promoters and in the origin of replication of adenovirus type 2. Other names for this target antigen include CTF5, NF-I, NFI, nuclear factor 1 C-type, CCAAT-box-binding transcription factor, and CTF.