Intracellular receptors are globular protein

receptor Receptor may refer to: * Sensory receptor, in physiology, any neurite structure that, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and respond ...

s located inside the cell rather than on its

cell membrane The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...

. The word ''intracellular'' means "within or inside a cell." Molecules that cross a cell membrane to bind with a receptor are generally nonpolar and may be relatively small. These molecules are also known as

ligands In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's ...

, these trigger how genes are turned on or off which are essential for processes like growth metabolism etc. Hormones that use intracellular receptors include thyroid,

aldosterone Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays ...

, and steroid hormones.

Mechanism of Intracellular Receptors

The process starts when a signaling molecule like hormones and binds to a specific receptor. # Binding: the molecule(hormone) bind to the intracellular receptor which changes its shape (induced-fit mechanism) and activates it. # Activation: the intracellular receptor moves to the nucleus if it wasn’t already in the nucleus. # DNA binding: the activated intracellular receptor binds to a specific part of the DNA called a hormone response element (HRE). # Gene regulation: the intracellular receptor either turns on or turns off the target gene which affects the production of proteins that control bodily processes

Examples

Examples are the class of

nuclear receptor In the field of molecular biology, nuclear receptors are a class of proteins responsible for sensing steroids, thyroid hormones, vitamins, and certain other molecules. These intracellular receptors work with other proteins to regulate the ex ...

s located in the

cell nucleus The cell nucleus (; : nuclei) is a membrane-bound organelle found in eukaryote, eukaryotic cell (biology), cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have #Anucleated_cells, ...

and

cytoplasm The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell a ...

and the IP₃ receptor located on the

endoplasmic reticulum The endoplasmic reticulum (ER) is a part of a transportation system of the eukaryote, eukaryotic cell, and has many other important functions such as protein folding. The word endoplasmic means "within the cytoplasm", and reticulum is Latin for ...

. The

ligand In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...

s that bind to them are usually intracellular second messengers like inositol trisphosphate (IP₃) and extracellular

lipophilic Lipophilicity (from Greek language, Greek λίπος "fat" and :wikt:φίλος, φίλος "friendly") is the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such compounds are c ...

hormone A hormone (from the Ancient Greek, Greek participle , "setting in motion") is a class of cell signaling, signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physio ...

s like steroid hormones. Some intracrine

peptide hormone Peptide hormones are hormones composed of peptide molecules. These hormones influence the endocrine system of animals, including humans. Most hormones are classified as either amino-acid-based hormones (amines, peptides, or proteins) or steroid h ...

s also have intracellular receptors.

Importance of Intracellular Receptors

# Growth and development: steroid hormones like testosterone and estrogen guide puberty and reproduction # Energy use: thyroid hormones regulate how the body uses energy which influences weight temperature and mood. # Stress Response: Cortisol, a stress hormone, binds to its receptor to help the body respond to challenges. # Immune System: Some intracellular receptors control inflammation and immune responses # See also *

Receptor Receptor may refer to: * Sensory receptor, in physiology, any neurite structure that, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and respond ...

* Steroid hormone

Challenges Faced by Intracellular Receptors

* Hormone Resistance: For example, in androgen insensitivity syndrome, the body can’t respond to testosterone. * Cancer: Overactive estrogen receptors can drive the growth of certain breast cancers. * Metabolic Disorders: Faulty thyroid hormone receptors can cause problems like weight gain, fatigue, and more

Therapies That Target Intracellular Receptors

Many medicines work by targeting intracellular receptors. For example: * Tamoxifen: A drug that blocks estrogen receptors to treat hormone-sensitive breast cancer. * Corticosteroids: Synthetic versions of cortisol that reduce inflammation in conditions like asthma and arthritis. * Thyroid Hormone Pills: Used to treat hypothyroidism when natural hormone levels are too low.

References

External links

''Nuclear Receptor'' journal homepage

Nuclear receptor resource

Nuclear receptor signalling atlas
(NURSA, open-access journal)

* {{Cell signaling Intracellular receptors,