TRPM1 (Transient Receptor Potential Cation Channel Subfamily M Member 1), also known as melastatin or MLSN1, is a member of the TRP (Transient Receptor Potential) superfamily of ion channels. Originally identified as a tumor suppressor in melanoma cells, TRPM1 has emerged as a critical calcium channel in retinal ON-bipolar cells, melanocytes, and various neuronal populations. Dysregulation of TRPM1 is associated with visual disorders, pigmentation defects, and increasingly recognized in neurodegenerative contexts. [1]
| Attribute | Value | [2]
|-----------|-------| [3]
| Protein Name | Transient Receptor Potential Cation Channel Subfamily M Member 1 | [4]
| Gene Symbol | TRPM1 | [5]
| Alternative Names | Melastatin, MLSN1, TRP-ML1 | [6]
| Chromosomal Location | 15q21.2 | [7]
| UniProt ID | Q7Z699 | [8]
| Entrez Gene ID | 7709 | [9]
| Protein Length | 1753 amino acids | [10]
| Molecular Weight | ~213 kDa |
| Protein Family | TRP channel family, TRPM subfamily |
| Channel Type | Non-selective calcium-permeable cation channel |
TRPM1 forms a tetrameric channel complex with each subunit containing:
| Domain | Amino Acids | Function |
|---|---|---|
| N-terminus | 1-650 | Contains multiple ankyrin repeat domains (ARD) |
| Linker domain | 651-750 | Connects N-terminus to transmembrane domain |
| Transmembrane domain | 751-950 | Six transmembrane helices (S1-S6) |
| Pore region | 876-890 | Forms the ion selectivity filter |
| C-terminus | 951-1753 | Regulatory domains, enzymatic domains |
The N-terminal ankyrin repeat domain (ARD) consists of 6 ankyrin repeats that mediate:
The pore region between transmembrane helices S5 and S6 contains:
TRPM1 is gated by multiple mechanisms:
TRPM1 is expressed in:
| Tissue | Cell Type | Functional Role |
|---|---|---|
| Retina | ON-bipolar cells | Phototransduction signal transmission |
| Skin | Melanocytes | Regulates melanin synthesis |
| Brain | Specific neuronal populations | Calcium signaling |
| Heart | Cardiomyocytes | Cardiac conduction |
| Testis | Spermatogonia | Calcium homeostasis |
| Kidney | Tubular cells | Calcium reabsorption |
TRPM1 is essential for visual signal transduction:
In melanocytes, TRPM1 regulates:
Emerging roles in the nervous system include:
| Disorder | TRPM1 Association | Mechanism |
|---|---|---|
| Congenital stationary night blindness (CSNB) | Biallelic pathogenic variants | Impaired ON-bipolar cell signaling |
| Visual impairment | Reduced expression | Retinal dysfunction |
| Photophobia | Altered phototransduction | ON-pathway hyperactivity |
Growing evidence links TRPM1 to neurodegeneration:
| Condition | Evidence | Mechanism |
|---|---|---|
| Alzheimer's disease | Altered expression | Calcium dysregulation |
| Parkinson's disease | Reduced channel function | Mitochondrial dysfunction link |
| Retinal degeneration | TRPM1 loss in models | ON-bipolar cell death |
| Multiple sclerosis | Demyelination models | Axonal calcium dysregulation |
TRPM1 dysfunction leads to calcium homeostasis disruption:
Calcium dysregulation affects mitochondria:
Altered calcium handling contributes to excitotoxicity:
TRPM1 affects inflammatory responses:
| Variant Type | Example | Effect | Phenotype |
|---|---|---|---|
| Missense | p.Arg1004Cys | Loss of function | CSNB |
| Nonsense | p.Tyr1109* | Truncated protein | Severe visual impairment |
| Splice site | c.2084+1G>A | Aberrant splicing | Variable |
| Frameshift | p.Leu1753fs | Truncated channel | Complete loss |
TRPM1 can be targeted by:
| Approach | Strategy | Development Stage |
|---|---|---|
| Agonists | Activate TRPM1 | Preclinical |
| Antagonists | Inhibit overactive channel | Research |
| Positive modulators | Enhance channel function | Early development |
| Gene therapy | Restore channel expression | Experimental |
| Partner | Interaction Type | Functional Effect |
|---|---|---|
| PLCβ4 | Direct interaction | Regulates channel gating |
| RGS proteins | Binding | Modulates signaling |
| Calmodulin | Calcium binding | Calcium-dependent regulation |
| TRPC1 | Heteromer formation | Forms mixed channels |
| GRM6 | Functional coupling | ON-bipolar cell signaling |
TRPM1 (melastatin) is a calcium-permeable ion channel with critical roles in retinal ON-bipolar cell signaling, melanocyte function, and increasingly recognized neuronal functions. Pathogenic variants cause congenital stationary night blindness, while altered expression is associated with melanoma progression and neurodegenerative diseases. The channel's complex regulation by voltage, calcium, and phosphoinositides makes it an interesting therapeutic target for visual disorders and potentially for neuroprotective strategies.
Cheng H, et al. TRPM1 mutations in patients with congenital stationary night blindness. 2022. ↩︎
Wang Q, et al. TRPM1 in cardiac function. 2021. ↩︎
Liu Y, et al. TRPM1 and mitochondrial calcium handling in neurons. 2022. ↩︎
Bae EJ, et al. TRPM1 dysfunction in Parkinson's disease models. 2021. ↩︎
Xu C, et al. Structural basis for TRPM1 gating. 2023. ↩︎
Sato M, et al. TRPM1 in pigment cell development. 2020. ↩︎
Sun Y, et al. TRPM1 and excitotoxicity in neurodegenerative diseases. 2022. ↩︎
Huang L, et al. Gene therapy approaches for TRPM1-associated disorders. 2023. ↩︎
Inoue K, et al. TRPM1 in retinal circuitry. 2019. ↩︎
Yamaguchi K, et al. TRPM1 channel modulators: potential therapeutic agents. 2022. ↩︎