Gene Symbol: TACR1
Gene Name: Tachykinin Receptor 1
Chromosomal Location: 2p12
Aliases: NK1R, NK-1R, Substance P Receptor, SPR
TACR1 encodes the neurokinin 1 (NK1) receptor, a G protein-coupled receptor that binds substance P and other tachykinins. It is widely expressed in the central and peripheral nervous systems and plays important roles in pain transmission, neuroinflammation, mood regulation, and stress responses.
¶ Protein Structure and Function
The TACR1 receptor is a seven-transmembrane GPCR with the following characteristics:
- Extracellular N-terminus: Contains ligand-binding sites
- Transmembrane domains: Seven alpha-helices spanning the membrane
- Intracellular C-terminus: Couples to G proteins and contains phosphorylation sites
- Ligand binding: High affinity for substance P (SP), with lower affinity for neurokinin A and B
Upon activation, TACR1 couples to:
- Gαq/11: Activates phospholipase C (PLC)
- IP3 production: Leads to intracellular Ca2+ release
- DAG formation: Activates protein kinase C (PKC)
- MAPK activation: Triggers downstream signaling cascades
TACR1 and substance P have been implicated in Alzheimer's disease:
- Neuroinflammation: TACR1 activation promotes microglial activation and pro-inflammatory cytokine release
- Amyloid metabolism: Substance P may affect amyloid precursor protein processing
- Cognitive function: NK1 receptor antagonists may have cognitive-enhancing effects
- Neuroprotection: Some studies suggest protective effects of substance P
In Parkinson's disease, TACR1 plays a role in:
- Motor function: Basal ganglia tachykinin signaling affects movement
- Neuroinflammation: Enhanced TACR1-mediated inflammation in the substantia nigra
- L-DOPA response: Potential involvement in treatment response and dyskinesias
¶ Depression and Anxiety
TACR1 is a major target for substance P antagonists:
- Major depressive disorder: NK1 receptor antagonists show antidepressant effects
- Anxiety disorders: Anxiolytic potential of TACR1 modulation
- Stress response: TACR1 in stress-induced neurodegeneration
¶ Pain and Migraine
- Pain transmission: TACR1 in nociceptive pathways
- Migraine: NK1 antagonists investigated for acute treatment
| Tissue/Cell Type |
Expression Level |
Notes |
| Brain |
High |
Cortex, hippocampus, thalamus |
| Spinal cord |
High |
Dorsal horn |
| Peripheral nerves |
High |
Sensory neurons |
| Immune cells |
Moderate |
Macrophages, lymphocytes |
| Gastrointestinal tract |
High |
Enteric nervous system |
TACR1 is a validated drug target:
- NK1 antagonists: Developed for depression, anxiety, and pain
- ** Substance P analogs:** Therapeutic peptides
- Antiemetics: Aprepitant, fosaprepitant (approved for chemotherapy-induced nausea)
- Depression: Aprepitant and other NK1 antagonists show efficacy
- Anxiety: Anxiolytic potential
- Pain: Analgesic effects in preclinical models
- Migraine: Ongoing investigation
- Chemotherapy-induced nausea: Approved indication
¶ Interactions and Pathways
TACR1 interacts with:
- Substance P (TAC1): Primary endogenous ligand
- β-arrestin: Mediates receptor internalization
- RACK1: Scaffold protein
- PDZ domain proteins: Regulatory interactions
- Phospholipase C pathway
- MAPK/ERK pathway
- NF-κB pathway
- Calcium signaling
TACR1 polymorphisms have been associated with:
- Depression susceptibility
- Pain perception
- Migraine risk
- Schizophrenia
- Gene-environment interactions in mood disorders
- Pharmacogenetics of NK1 antagonists
- How does TACR1 contribute to neuroinflammation in AD and PD?
- Can NK1 antagonists provide disease-modifying effects?
- What is the role of substance P in alpha-synuclein aggregation?
- TACR1 antagonists for neurodegenerative diseases
- Understanding neuroinflammation modulation
- Biomarker development