Sub-families in the nuclear receptor superfamily:

Type I: Steroid receptors

• Translocation to the nucleus upon ligand binding.
• Bind as homodimers to inverted repeated DNA elements.
• Includes the glucocorticoid (GR), estrogen (ER), mineralocorticoid (MR), and androgen receptors (AR)

Type II: RXR heterodimers

• Localised in the nucleus independent of ligand binding.
• Binds as heterodimers with RXR to direct repeats of DNA elements.
• Includes RAR, vitamin D receptor (VDR), thyroid receptor (TR), PPAR, liver X receptor (LXR).

Type III: orphan NRs

• Dimers, monomers of ”orphan” receptors: unknown ligand or no ligand?