Intracellular receptors or nuclear receptors are a class of receptor located inside the cell rather than on its cell membrane. Their ligands (substances that bind to them) are hormones, eicosanoids, vitamins (vitamin A and vitamin D) and various other substances. In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific factor (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ... Cells in culture, stained for keratin (red) and DNA (green) The cell is the structural and functional unit of all living organisms, and are sometimes called the building blocks of life. ... Drawing of a cell membrane A component of every biological cell, the selectively permeable cell membrane (or plasma membrane or plasmalemma) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ... In chemistry, a ligand is an atom, ion or functional group that is bonded to one or more central atoms or ions, usually metals generally through coordinate covalent bond. ... A hormone (from Greek horman - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... In biochemistry, eicosanoids are a class of oxygenated hydrophobic cytokines that largely function as a autocrine and paracrine mediators. ... A Vitamin is an organic molecule required by a living organism in minute amounts for proper health. ... Retinol, the dietary form of vitamin A, is a fat-soluble, antioxidant vitamin important in vision and bone growth. ... Vitamin D is a fat soluble vitamin that contributes to the maintenance of normal levels of calcium and phosphorus in the bloodstream. ...

Practically all intracellular receptors are transcription factors; when activated they migrate to the nucleus and bind to DNA, stimulating or suppressing gene transcription. Many receptors require dimerisation (binding either another receptor of the same type, a different type or even a different protein). Some intracellular receptors also appear to interact with other signal transduction mechanisms. In the context of genetics, a transcription factor is a regulatory protein that initiates the transcription of certain genes upon binding with DNA. The binding of a transcription factor to a specific DNA sequence can result in either an increased rate of transcription of the gene, known as activated transcription... In cell biology, the nucleus (from Latin nucleus or nuculeus, kernel) is found in all eukaryotic cells that contains most of the cells genetic material. ... Space-filling model of a section of DNA molecule Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions specifying the biological development of all cellular forms of life (and most viruses). ... Transcription is the process through which a DNA sequence is enzymatically copied by an RNA polymerase to produce a complementary RNA. Or, in other words, the transfer of genetic information from DNA into RNA. In the case of protein-encoding DNA, transcription is the beginning of the process that ultimately... Sucrose, or common table sugar, is composed of glucose and fructose. ... In biology, signal transduction is any process by which a cell converts one kind of signal or stimulus into another. ...

Members

Transcription factors

• Steroid hormone receptor:
  • Sex hormone receptors (sex hormones)
    • Estrogen receptor (α and β)
    • Androgen receptor (one type)
  • Vitamin D receptor (vitamin D, one type)
  • Glucocorticoid receptor (glucocorticoids, one type)
  • Mineralocorticoid receptor (mineralocorticoids, one type)
• Thyroid hormone receptor (α and β)
• Retinoid receptor (vitamin A and related compounds);
• Peroxisome proliferator-activated receptors (PPARs, α, γ and δ)

In the context of genetics, a transcription factor is a regulatory protein that initiates the transcription of certain genes upon binding with DNA. The binding of a transcription factor to a specific DNA sequence can result in either an increased rate of transcription of the gene, known as activated transcription... Steroid hormone receptors are generally intracellular (specifically cytoplasmatic) receptors that perform signal transduction for steroid hormones. ... Sex hormone receptors belong to the group of steroid hormone receptors and interact with sex hormones. ... Sex hormones are hormones that affect the reproductive system. ... The estrogen receptor is a receptor for estradiol (the main endogenous estrogen); it is located intracellularly, in parallel with other steroid hormone receptors. ... The androgen receptor is an intracellular steroid receptor that specifically binds testosterone and dihydrotestosterone,- it has two main forms, A and B, that differ in their molecular weight. ... Vitamin D is a fat soluble vitamin that contributes to the maintenance of normal levels of calcium and phosphorus in the bloodstream. ... The ‘’’glucocorticoid receptor’’’ (GR) is a ligand-activated intracytoplasmatic transcription factor that interacts with high affinity to cortisol and other glucocorticoids. ... Glucocorticoids are a class of steroid hormones characterised by an ability to bind with the cortisol receptor and trigger similar effects. ... Mineralocorticoids is a class of steroids characterised by their similarity to aldosterone and their influence on salt and water metabolism. ... Retinol, the dietary form of vitamin A, is a fat-soluble, antioxidant vitamin important in vision and bone growth. ... In cell biology, peroxisome proliferator-activated receptors (PPARs) are a group of nuclear receptor isoforms that exist across biology. ...

Various

• sigma1 (neurosteroids))
• IP₃ receptor (inositol triphosphate, IP₃)

Apart from exerting effects on the genome via intracellular steroid receptors, neuroactive steroids (or neurosteroids) rapidly alter neuronal excitability through interaction with neurotransmitter-gated ion channels. ... Inositol triphosphate or inositol 1,4,5-triphosphate (also commonly known as triphosphoinositol; abbreviated InsP3 or IP3), together with diacylglycerol, is a second messenger molecule used in signal transduction in biological cells. ...

External links

• Nuclear Receptor journal homepage
• Nuclear receptor resource at Georgetown University
• Nuclear receptor signalling atlas (NURSA, open-access journal)