Monoamine neurotransmitters are neurotransmitter

Neurotransmitter

Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to...

s and neuromodulators that contain one amino group that is connected to an aromatic

Aromaticity

In organic chemistry, Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. The earliest use of the term was in an article by August...

 ring by a two-carbon chain (-CH₂-CH₂-). All monoamines are derived from aromatic amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

s like phenylalanine

Phenylalanine

Phenylalanine is an α-amino acid with the formula C6H5CH2CHCOOH. This essential amino acid is classified as nonpolar because of the hydrophobic nature of the benzyl side chain. L-Phenylalanine is an electrically neutral amino acid, one of the twenty common amino acids used to biochemically form...

, tyrosine

Tyrosine

Tyrosine or 4-hydroxyphenylalanine, is one of the 22 amino acids that are used by cells to synthesize proteins. Its codons are UAC and UAU. It is a non-essential amino acid with a polar side group...

, tryptophan

Tryptophan

Tryptophan is one of the 20 standard amino acids, as well as an essential amino acid in the human diet. It is encoded in the standard genetic code as the codon UGG...

, and the thyroid hormone

Thyroid hormone

The thyroid hormones, thyroxine and triiodothyronine , are tyrosine-based hormones produced by the thyroid gland primarily responsible for regulation of metabolism. An important component in the synthesis of thyroid hormones is iodine. The major form of thyroid hormone in the blood is thyroxine ,...

s by the action of aromatic amino acid decarboxylase enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

s.

Examples

• Histamine
  Histamine
  Histamine is an organic nitrogen compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by...
  
  
• Catecholamine
  Catecholamine
  Catecholamines are molecules that have a catechol nucleus consisting of benzene with two hydroxyl side groups and a side-chain amine. They include dopamine, as well as the "fight-or-flight" hormones adrenaline and noradrenaline released by the adrenal medulla of the adrenal glands in response to...
  
  s:
  • Dopamine
    Dopamine
    Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
    
     (DA)
  • Noradrenaline (NA) (Norepinephrine, NE)
  • Adrenaline  (Epinephrine)
• Tryptamine
  Tryptamine
  Tryptamine is a monoamine alkaloid found in plants, fungi, and animals. It is based around the indole ring structure, and is chemically related to the amino acid tryptophan, from which its name is derived...
  
  s:
  • Serotonin
    Serotonin
    Serotonin or 5-hydroxytryptamine is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system of animals including humans...
    
     (5-HT)
  • Melatonin
    Melatonin
    Melatonin , also known chemically as N-acetyl-5-methoxytryptamine, is a naturally occurring compound found in animals, plants, and microbes...
    
    
• Trace amine
  Trace amine
  Trace amines are endogenous compounds structurally related to classical biogenic amines, such as catecholamines, serotonin and histamine. Trace amines include p-tyramine, β-phenylethylamine, tryptamine, octopamine, and 3-iodothyronamine, and are found in the nervous systems of animals from insects...
  
  s:
  • β-Phenylethylamine (PEA, β-PEA)
  • Tyramine
    Tyramine
    Tyramine is a naturally occurring monoamine compound and trace amine derived from the amino acid tyrosine. Tyramine acts as a catecholamine releasing agent...
    
    
  • Tryptamine
    Tryptamine
    Tryptamine is a monoamine alkaloid found in plants, fungi, and animals. It is based around the indole ring structure, and is chemically related to the amino acid tryptophan, from which its name is derived...
    
    
  • Octopamine
    Octopamine
    Octopamine is an endogenous biogenic amine that is closely related to norepinephrine, and has effects on the adrenergic and dopaminergic systems. It is also found naturally in numerous plants, including bitter orange. Biosynthesis of the D--enantiomer of octopamine is by β-hydroxylation of...
    
    
  • 3-Iodothyronamine
    3-Iodothyronamine
    3-Iodothyronamine is an endogenous thyronamine. T1AM is a high-affinity ligand for the trace amine-associated receptor TAAR1 , a G protein-coupled receptor...
    
    
  • Thyronamine
    Thyronamine
    Thyronamine refers both to a molecule, and to derivatives of that molecule: a family of decarboxylated and deiodinated metabolites of the thyroid hormones thyroxine and 3,5,3'-triiodothyronine .-Types:The group includes:* Thyronamine...
    
    s, a new group of compounds derived from thyroid hormones

Specific transporter protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s called monoamine transporter

Monoamine transporter

Monoamine transporters are protein structures that function as integral plasma membrane transporters to regulate concentrations of extracellular monoamine neurotransmitters. Three major classes of MATs are responsible for the reuptake of their associated amine neurotransmitters...

s that transport monoamines in or out of a cell exist. These are the dopamine transporter

Dopamine transporter

The dopamine transporter is a membrane-spanning protein that pumps the neurotransmitter dopamine out of the synapse back into cytosol, from which other transporters sequester DA and NE into vesicles for later storage and release...

 (DAT), serotonin transporter

Serotonin transporter

The serotonin transporter is a monoamine transporter protein.This protein is an integral membrane protein that transports the neurotransmitter serotonin from synaptic spaces into presynaptic neurons. This transport of serotonin by the SERT protein terminates the action of serotonin and recycles it...

 (SERT), and the norepinephrine transporter

Norepinephrine transporter

The norepinephrine transporter , also known as solute carrier family 6 member 2 , is a protein that in humans is encoded by the SLC6A2 gene....

 (NET) in the outer cell membrane

Cell membrane

The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...

 and the vesicular monoamine transporter

Vesicular monoamine transporter

The vesicular monoamine transporter is a transport protein integrated into the membrane of intracellular vesicles of presynaptic neurons. It acts to transport monoamines into the synaptic vesicles.-Monoamines:...

 (VMAT1

VMAT1

VMAT1 is a protein that transports the monoamines into intracellular vesicles.In chromaffin cells, it is responsible for transporting newly synthesized epinephrine from the cytosol back into chromaffin granules in preparation for release.For norepinephrine to be acted upon by PNMT in the cytosol,...

 and VMAT2

VMAT2

The vesicular monoamine transporter 2 also known as solute carrier family 18 member 2 is a protein that in humans is encoded by the SLC18A2 gene...

) in the membrane of intracellular vesicle

Vesicle (biology)

A vesicle is a bubble of liquid within another liquid, a supramolecular assembly made up of many different molecules. More technically, a vesicle is a small membrane-enclosed sack that can store or transport substances. Vesicles can form naturally because of the properties of lipid membranes , or...

s.

After release into the synaptic cleft, monoamine neurotransmitter action is ended by reuptake into the presynaptic terminal. There, they can be repackaged into synaptic vesicles or degraded by the enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 monoamine oxidase

Monoamine oxidase

L-Monoamine oxidases are a family of enzymes that catalyze the oxidation of monoamines. They are found bound to the outer membrane of mitochondria in most cell types in the body. The enzyme was originally discovered by Mary Bernheim in the liver and was named tyramine oxidase...

 (MAO), which is a target of monoamine oxidase inhibitors, a class of antidepressants.

See also

• Monoamine oxidase
  Monoamine oxidase
  L-Monoamine oxidases are a family of enzymes that catalyze the oxidation of monoamines. They are found bound to the outer membrane of mitochondria in most cell types in the body. The enzyme was originally discovered by Mary Bernheim in the liver and was named tyramine oxidase...
  
  
• Monoamine transporter
  Monoamine transporter
  Monoamine transporters are protein structures that function as integral plasma membrane transporters to regulate concentrations of extracellular monoamine neurotransmitters. Three major classes of MATs are responsible for the reuptake of their associated amine neurotransmitters...
  
  
• Neurotransmitter
  Neurotransmitter
  Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to...
  
  
• Monoamine Hypothesis