Mechanism of Action
Nuclear receptors (NRs) may be classified into two broad classes according to their mechanism of action and subcellular distribution in the absence of ligand.
Small lipophilic substances such as natural hormones diffuse past the cell membrane and bind to nuclear receptors located in the cytosol (type I NR) or nucleus (type II NR) of the cell. This causes a change in the conformation of the receptor, which, depending on the mechanistic class (type I or II), triggers a number of down stream events that eventually results in up or down regulation of gene expression. In addition, two additional classes, type III which are a variant of type I, and type IV that bind DNA as monomers have also been defined.
Accordingly, nuclear receptors may be subdivided into the following four mechanistic classes:
Read more about this topic: Nuclear Receptor
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