SLC39A9 (Solute Carrier Family 39 Member 9), also known as ZIP9, is a member of the ZIP (Zrt-, Irt-like Protein) family of zinc transporters. It is encoded by the SLC39A9 gene located on chromosome 14q24 and functions as a membrane transporter that facilitates zinc uptake into cells. ZIP transporters are essential for maintaining cellular zinc homeostasis, which is critical for numerous biological processes including enzyme function, gene expression, immune response, and neuronal signaling. SLC39A9 is expressed in various tissues, including brain, kidney, liver, and immune cells, where it contributes to zinc homeostasis. Emerging research suggests that altered zinc transport may be relevant to neurodegenerative diseases including Alzheimer's disease and Parkinson's disease. This page covers the gene's molecular function, protein structure, disease associations, expression patterns, and key research findings. [1][2]
| Property | Value |
|---|---|
| Gene Symbol | SLC39A9 |
| Alternative Names | ZIP9, Zrt- and Irt-like protein 9 |
| Chromosomal Location | 14q24 |
| Ensembl ID | ENSG00000117281 |
| NCBI Gene ID | 55334 |
| OMIM | 607343 |
| UniProt ID | Q9NVA1 |
| Protein Length | 295 amino acids |
| Molecular Weight | ~32 kDa |
SLC39A9 (ZIP9) is a membrane protein with characteristic features of the ZIP family:
ZIP family proteins typically contain 8 transmembrane helices:
The protein contains potential metal-binding motifs:
The cytoplasmic N-terminus and C-terminus:
ZIP transporters likely function as dimers or higher-order oligomers:
SLC39A9 facilitates zinc uptake through the following mechanism:
ZIP transporters operate through a proton-coupled or bicarbonate-dependent antiport mechanism:
SLC39A9 can transport multiple divalent metals:
SLC39A9 activity is regulated at multiple levels:
SLC39A9 interacts with several proteins involved in zinc homeostasis:
SLC39A9 exhibits broad tissue distribution:
| Tissue/Cell Type | Expression Level |
|---|---|
| Kidney | High |
| Liver | High |
| Brain | Moderate-High |
| Lung | Moderate |
| Testis | Moderate |
| Spleen | Low-Moderate |
| Heart | Low |
| Skeletal Muscle | Low |
In the brain, SLC39A9 is expressed in:
Brain regions with high expression include:
Expression is cell-type specific and regulated by:
SLC39A9 has emerging relevance to AD through several mechanisms:
Zinc Homeostasis: Zinc is essential for normal brain function and is implicated in AD pathogenesis. Zinc plays roles in:
Zinc and Amyloid: Zinc can promote amyloid-beta aggregation and plaque formation. Altered zinc transporter function may contribute to this process. Zinc binding to amyloid-beta stabilizes toxic oligomers.
Synaptic Zinc: Synaptic zinc is released during neurotransmission and affects synaptic plasticity. Dysregulated zinc signaling may contribute to cognitive decline in AD.
Therapeutic Implications: Modulating zinc transport through SLC39A9 could potentially affect AD pathology, though the complexity of zinc biology makes this challenging.
SLC39A9 may be relevant to PD through:
Zinc and Dopaminergic Neurons: Zinc homeostasis is important for dopaminergic neuron survival. Altered zinc levels may contribute to neurodegeneration in the substantia nigra.
Mitochondrial Function: Zinc is required for mitochondrial enzymes. Altered zinc transport could affect mitochondrial function, relevant to PD pathogenesis.
Alpha-Synuclein: Zinc may affect alpha-synuclein aggregation. Zinc transporter function could influence this process.
Neuroinflammation: Zinc modulates microglial activation. Altered zinc homeostasis may affect neuroinflammatory responses in PD.
Altered SLC39A9 expression has been reported in several cancers:
Zinc is critical for immune system function:
SLC39A9 expression in immune cells may contribute to these processes.
High SLC39A9 expression in kidney suggests roles in:
Mus musculus:
Zebrafish: ZIP9 homolog studied in development
SLC39A9 is clinically relevant in several contexts: