Transcription factors can exist in the nucleus as dimers because the formation of disulfide bonds is not the only way to form dimers. Dimers can also form through hydrophobic interactions, hydrogen bonds, and ionic bonds. For example, LysR-type transcriptional regulators (LTTRs) can form dimers via the N terminal DNA binding domain and the C-terminal cofactor binding domain. TFs can thus have monomer or dimer specific interactions with the DNA.

Another example of a TF that can exist as a dimer: Article A dimer-specific function of the transcription factor NFATp