Htr2C Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
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| Attribute |
Value |
| Protein Name |
HTR2C, 5-Hydroxytryptamine Receptor 2C |
| Gene Symbol |
htr2c |
| UniProt ID |
P28335 |
| Molecular Weight |
~60-70 kDa |
| Subcellular Localization |
Cell membrane, caveolin-rich domains |
| Protein Family |
Class A GPCR, 5-HT2 family |
| Ligand |
Serotonin (5-HT), lysergic acid diethylamide (LSD) |
| Signal Transduction |
Gq protein, PLCβ, IP3, Ca²⁺, ERK1/2 |
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The 5-Hydroxytryptamine Receptor 2C (5-HT₂C or HTR2C) is a G protein-coupled receptor that binds the neurotransmitter serotonin (5-hydroxytryptamine, 5-HT). This receptor is widely expressed in the central nervous system and plays diverse roles in mood regulation, appetite, sleep, cognition, and motor control. The HTR2C receptor is uniquely regulated by RNA editing, which produces multiple receptor isoforms with distinct signaling properties.
HTR2C has the typical seven-transmembrane domain structure of class A GPCRs:
¶ Extracellular Domain
- N-terminal tail: Short extracellular sequence
- Loop regions: Connect transmembrane helices
¶ Transmembrane Domain
- Seven α-helices: Cross the lipid bilayer
- Conserved motifs: For ligand binding and G protein coupling
- Orthosteric binding site: In the transmembrane core
¶ Intracellular Domain
- C-terminal tail: Long intracellular tail with multiple phosphorylation sites
- RNA editing site: A site in the coding sequence (positions 156, 157, 158)
- PDZ-binding motif: For protein-protein interactions
The HTR2C receptor undergoes A-to-I RNA editing:
- Non-edited (AAA): Produces unedited isoform with highest signaling
- Partially edited (AGA, AAG, GGG): Intermediate signaling
- Fully edited (GGG): Reduced signaling efficiency
HTR2C activates the Gq/11 protein signaling pathway:
- Serotonin binding induces receptor conformational change
- Gq/11 protein activation
- Phospholipase Cβ (PLCβ) activation
- PIP₂ hydrolysis → IP₃ + DAG
- Intracellular calcium release
- PKC activation and ERK1/2 phosphorylation
- Mood regulation: Anxiolytic and antidepressant effects
- Appetite control: Satiety signaling, obesity target
- Sleep-wake cycle: REM sleep regulation
- Motor behavior: Spontaneous locomotor activity
- Cognition: Working memory and executive function
- Thermoregulation: Body temperature control
HTR2C is expressed in:
- Choroid plexus (highest)
- Hypothalamus
- Cortex (layers II-III, VI)
- Hippocampus
- Basal ganglia
- Amygdala
- Serotonergic dysfunction: Altered 5-HT₂C expression in AD brains
- Behavioral symptoms: 5-HT₂C contributes to depression and anxiety in AD
- Amyloid effects: Aβ may modulate 5-HT₂C signaling
- Therapeutic targeting: 5-HT₂C agonists for behavioral symptoms
- Motor complications: 5-HT₂C involved in L-DOPA-induced dyskinesias
- Depression: Serotonergic system changes in PD
- Evidence: Altered HTR2C expression in PD putamen
- Therapeutic potential: 5-HT₂C antagonists for dyskinesias
- Serotonergic dysfunction: Altered 5-HT₂C in ALS motor cortex
- Motor neuron function: 5-HT₂C modulates motor neuron excitability
- Evidence: Changed receptor expression in ALS tissue
- Mood disorders: Depression and anxiety in HD
- Motor dysfunction: 5-HT₂C in chorea and dyskinesias
- Therapeutic targeting: 5-HT₂C modulators for HD symptoms
- Behavioral symptoms: Agitation, disinhibition
- Serotonergic changes: 5-HT system alterations in FTD
| Drug Class |
Mechanism |
Example |
Status |
| Agonists |
Activate receptor |
Lorcaserin |
Approved (obesity) |
| Antagonists |
Block receptor |
SB-242084 |
Preclinical |
| NAMs |
Reduce signaling |
CM-6825 |
Preclinical |
| PAMs |
Enhance signaling |
VU-03601872 |
Research |
- Obesity: Lorcaserin (withdrawn), 5-HT₂C agonists for weight loss
- Depression: 5-HT₂C in mood disorder treatment
- Dyskinesias: 5-HT₂C antagonists for L-DOPA-induced dyskinesias
- Schizophrenia: 5-HT₂C in antipsychotic action
- Anxiety: Anxiolytic potential of 5-HT₂C modulation
- Addiction: 5-HT₂C in reward and substance abuse
- Epilepsy: 5-HT₂C in seizure susceptibility
- CSF 5-HT₂C levels as neurotransmitter marker
- RNA editing status as biological marker
- PET ligands for receptor imaging
- HTR2C polymorphisms in neurodegenerative diseases
- Epigenetic regulation of HTR2C expression
- Cryo-EM structures of 5-HT₂C
- Allosteric binding site characterization
- HTR2C knockout mice: Obese, prone to seizures
- Humanized mice: Expressing human HTR2C
- Conditional knockouts: Tissue-specific deletion
- Transgenic models: Overexpression and disease models
The study of Htr2C Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.