Nuclear receptors are a class of intracellular receptors. They are located inside the cell rather than on its outer cell membrane. The ligands that bind to nuclear receptors are often lipophilic hormones like steroid hormones. Practically all intracellular receptors are transcription factors. When activated they migrate to the cell nucleus and bind to DNA and stimulate or suppress gene transcription. Many receptors require dimerisation (binding either another receptor of the same type, a different type or even a different protein). Some intracellular receptors also appear to interact with other signal transduction mechanisms.

(source: Wikipedia)

Invitrogen		Nuclear Receptors
		FRET NR coactivator assays
DiscoverX		http://www.discoverx.com/products.php?p=13
University of Georgetown		Nuclear receptor resource
PPAR resource pages		http://ppar.cas.psu.edu/
Nuclear Receptor reource		http://nrr.georgetown.edu/NRR/NRR1.html

Thyroid hormone-like receptors HNF3-like receptors Estrogen-like receptors PPAR PPAR- alpha PPAR- gamma LXR FXR