biology

TAAR1

TAAR1 is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand TAAR1 rather than just read about it. In short: Trace amine-associated receptor 1 (TAAR1) is a trace amine-associated receptor (TAAR) protein that in humans is encoded by the TAAR1 gene. TAAR1 is a primarily intracellular amine-activated Gs-coupled and Gq-coupled G protein-coupled receptor (GPCR) that is primarily expressed in several peripheral organs and cells (e.g., the stomach, small intestine, duodenum, and white blood cells), astrocytes, and in the intracel…

Key takeaways

TAAR1 belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect TAAR1 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of TAAR1 from memory before moving on to harder problems.

Reference excerpt

Trace amine-associated receptor 1 (TAAR1) is a trace amine-associated receptor (TAAR) protein that in humans is encoded by the TAAR1 gene. TAAR1 is a primarily intracellular amine-activated Gs-coupled and Gq-coupled G protein-coupled receptor (GPCR) that is primarily expressed in several peripheral organs and cells (e.g., the stomach, small intestine, duodenum, and white blood cells), astrocytes, and in the intracellular milieu within the presynaptic plasma membrane (i.e., axon terminal) of monoamine neurons in the central nervous system (CNS). TAAR1 is one of six functional human TAARs, which are so named for their ability to bind endogenous amines that occur in tissues at trace concentrations. TAAR1 plays a significant role in regulating neurotransmission in dopamine, norepinephrine, and serotonin neurons in the CNS; it also affects immune system and neuroimmune system function through different mechanisms. Endogenous ligands of the TAAR1 include trace amines, monoamine neurotransmitters, and certain thyronamines. The trace amines β-phenethylamine, tyramine, tryptamine, and octopamine, the monoamine neurotransmitters dopamine and serotonin, and the thyronamine 3-iodothyronamine (3-IT) are all agonists of the TAAR1 in different species. Other endogenous agonists are also known. A variety of exogenous compounds and drugs are TAAR1 agonists as well, including various phenethylamines, amphetamines, tryptamines, and ergolines, among others. There are marked species differences in the interactions of ligands with the TAAR1, resulting in greatly differing affinities, potencies, and efficacies of TAAR1 ligands between species. Many compounds that are TAAR1 agonists in rodents are much less potent or inactive at the TAAR1 in humans. A number of selective TAAR1 ligands have been developed, for instance the TAAR1 full agonist RO5256390, the TAAR1 partial agonist RO5263397, and the TAAR1 antagonists EPPTB and RTI-7470-44. Selective TAAR1 agonists are used in scientific research, and a few TAAR1 agonists, such as ulotaront and ralmitaront, are being developed as novel pharmaceutical drugs, for instance to treat schizophrenia and substance use disorder.

Discovery The TAAR1 was discovered in 2001 by two independent groups, Borowski et al. and Bunzow et al.. To find the genetic variants responsible for TAAR1 synthesis, they used mixtures of oligonucleotides with sequences related to G protein-coupled receptors (GPCRs) of serotonin and dopamine to discover novel DNA sequences in rat genomic DNA and cDNA, which they then amplified and cloned. The resulting sequence was not found in any database and coded for TAAR1. Further characterization of the functional role of TAAR1 and other receptors from this family was performed by other researchers including Raul Gainetdinov and his colleagues.

Structure TAAR1 shares structural similarities with the class A rhodopsin GPCR subfamily. It has 7 transmembrane domains with short N and C terminal extensions. TAAR1 is 62–96% identical with TAARs2-15, which suggests that the TAAR subfamily has recently evolved; while at the same time, the low degree of similarity between TAAR1 orthologues suggests that they are rapidly evolving. TAAR1 shares a predictive peptide motif with all other TAARs. This motif overlaps with transmembrane domain VII, and its identity is NSXXNPXX[Y,H]XXX[Y,F]XWF. TAAR1 and its homologues have ligand pocket vectors that utilize sets of 35 amino acids known to be involved directly in receptor-ligand interaction.

Gene All human TAAR genes are located on a single chromosome spanning 109 kb of human chromosome 6q23.1, 192 kb of mouse chromosome 10A4, and 216 kb of rat chromosome 1p12. Each TAAR is derived from a single exon, except for TAAR2, which is coded by two exons. The human TAAR1 gene is thought to be an intronless gene.

Tissue distribution

To date, TAAR1 has been identified and cloned in five different mammal genomes: human, mouse, rat, monkey, and chimpanzee. In rats, mRNA for TAAR1 is found at low to moderate levels in peripheral tissues like the stomach, kidney, intestines and lungs, and at low levels in the brain. Rhesus monkey Taar1 and human TAAR1 share high sequence similarity, and TAAR1 mRNA is highly expressed in the same important monoaminergic regions of both species. These regions include the dorsal and ventral caudate nucleus, putamen, substantia nigra, nucleus accumbens, ventral tegmental area, locus coeruleus, amygdala, and raphe nucleus. hTAAR1 has also been identified in human astrocytes. Outside of the human central nervous system, hTAAR1 also occurs as an intracellular receptor and is primarily expressed in the stomach, intestines, duodenum, pancreatic β-cells, and white blood cells. In the duodenum, TAAR1 activation increases glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) release; in the stomach, hTAAR1 activation has been observed to increase somatostatin (growth hormone-inhibiting hormone) secretion from delta cells. hTAAR1 is the only human trace amine-associated receptor subtype that is not expressed within the human olfactory epithelium.

Location within neurons TAAR1 is a primarily intracellular receptor expressed within the presynaptic terminal of monoamine neurons in humans and other animals. In model cell systems, hTAAR1 has extremely poor membrane expression. A method to induce hTAAR1 membrane expression has been used to study its pharmacology via a bioluminescence resonance energy transfer cAMP assay.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with TAAR1

Start with the simplest possible case. Write down what TAAR1 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to TAAR1 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about TAAR1 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of TAAR1

In research: TAAR1 appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses TAAR1 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: TAAR1 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Amphetamine, G protein-coupled receptors, Genes on human chromosome 6, so understanding it makes those chapters shorter.
In everyday life: Look for TAAR1 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study TAAR1 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what TAAR1 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain TAAR1 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is TAAR1 in simple terms?

Why does TAAR1 matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study TAAR1?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on TAAR1.