Subclasses within structural class 4
| Code | Subclass | Examples | |
|---|---|---|---|
| 4.1 | Nonsteroid receptors | ||
| This subclass comprises the heterodimeric receptors for nonsteroid ligands including retinoic acid, thyroid hormone, and vitamin D | 4.1 | TH VITD3 | |
| 4.2 | Steroid receptors | ||
| This subclass comprises the homodimeric receptors for steroids including cortisone, aldosterone, progesterone, and testosterone | 4.2 | PROG | |
(transcriptional regulator receptors)
Nuclear receptors constitute a distinctive class which has great therapeutic relevance but recently has been overlooked somewhat by pharmacologists. With the discovery of multiple orphan nuclear receptors and hence of other potential structural subclasses (seeKastner et al., 1995; Mangelsdorf et al., 1995; Laudet et al., 1998), we suggest that effort should be applied to further subclassification of this class on the basis of the integrated pharmacological approach proposed here.