Receptors that regulate gene transcription

These are also known as Nuclear receptors, though some are actually located in cytosol rather than the nuclear compartment.

Eg. : receptors for steroid hormones, thyroid hormone, Vit – D etc.

Most receptors are located in the nucleus and the ligands are all lipophilic compounds which can actually cross the cell membrane.

For eg., Glucocorticoids inhibit transcription of the gene for cyclo oxygenase-2 (Cox -2) which may account for their anti – inflammatory properties whereas mineralocorticoids stimulate the production of various transport proteins involved in renal tubular function.

The absorption of salt is under the control of the mineralocorticoid, aldosterone which enhances Sodium reabsorption and promotes Potassium excretion and it has a delayed effect by binding to receptors within the cell and directing the synthesis of a specific mediator protein that activates the Sodium channels.

References:

• Pharmacology by H.P.Rang, M.M.Dale and J.M.Ritter.

• Essentials of Medical Pharmacology by K.D.Tripathi