Principles of Biochemistry

9.2.3 Receptors of hormones

Receptors of hormones are protein macromolecules and glycoprotein in nature. Hormone molecules reach the target cells where they become bound by receptors. There are two types of receptors (i) membrane bound receptors and (ii) cytosol receptors.

(i) Membrane bound receptors: Receptors which bind the peptide hormones are present on the cell membrane, that is they partly protrude in the ECF and partly remain within the membrane.

a. cAMP- Epinephrin, norepinephrin, glucagon, leutinising hormone follicle stimulating hormone, thyroid stimulating hormone

b. cGMP -Atrial naturetic hormone

c. Calcium and/or phosphoinositides-Epinephrin, norepinephrin, angiotensin II, antidiuretic hormone, gonadotropin-releasing hormone, thyroid-releasing hormone

(ii)Cytosol receptors: Cytosol receptors occur either in the cytosol or on the nucleus. E.g. Receptors of thyroid and steroid hormones

The receptor has two domains:

1. Recognition domain that binds the hormone
2. Coupling domain that generates signal