APLP1 Gene

APLP1 (Amyloid Precursor-Like Protein 1)

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">APLP1 Gene</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>APLP1</td></tr>
<tr><td><strong>Full Name</strong></td><td>Amyloid Beta Precursor-Like Protein 1</td></tr>
<tr><td><strong>Chromosomal Location</strong></td><td>19q13.3</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[333](https://www.ncbi.nlm.nih.gov/gene/333)</td></tr>
<tr><td><strong>OMIM</strong></td><td>[104775](https://www.omim.org/entry/104775)</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000105248</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q15804](https://www.uniprot.org/uniprot/Q15804)</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>[Alzheimer's Disease](/diseases/alzheimers-disease), [Cognitive Decline](/diseases/cognitive-decline)</td></tr>
</table>
</div>

Overview

APLP1 (Amyloid Precursor-Like Protein 1)

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">APLP1 Gene</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>APLP1</td></tr>
<tr><td><strong>Full Name</strong></td><td>Amyloid Beta Precursor-Like Protein 1</td></tr>
<tr><td><strong>Chromosomal Location</strong></td><td>19q13.3</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[333](https://www.ncbi.nlm.nih.gov/gene/333)</td></tr>
<tr><td><strong>OMIM</strong></td><td>[104775](https://www.omim.org/entry/104775)</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000105248</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q15804](https://www.uniprot.org/uniprot/Q15804)</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>[Alzheimer's Disease](/diseases/alzheimers-disease), [Cognitive Decline](/diseases/cognitive-decline)</td></tr>
</table>
</div>

Overview

The APLP1 gene encodes Amyloid Precursor-Like Protein 1, a member of the highly conserved APP (Amyloid Precursor Protein) family that includes [APP](/genes/app), APLP1, and APLP2. While APLP1 cannot generate amyloid-beta (Abeta) peptides due to the absence of the Abeta coding region, it shares extensive structural and functional homology with APP and plays crucial roles in synaptic formation, neuronal survival, and cognitive function. APLP1 is a type I transmembrane glycoprotein expressed predominantly in the nervous system, where it participates in diverse cellular processes including synapse development, plasticity, and network excitability.

Gene Structure and Evolution

The APLP1 gene is located on chromosome 19q13.3 and consists of multiple exons encoding a protein of approximately 770 amino acids. The gene structure shows conserved exon-intron organization shared with other APP family members, reflecting their evolutionary relationship from a common ancestor gene. APLP1 exhibits several splice variants resulting from alternative splicing of the extracellular domain, creating protein isoforms with distinct temporal and spatial expression patterns.

Protein Structure and Domains

The APLP1 protein contains several conserved structural domains. The extracellular domain includes an N-terminal signal peptide, the E1 domain with heparin-binding region and copper-binding motif (HCQ4), the E2 domain, and the E3 domain. A single hydrophobic transmembrane helix anchors the protein in the plasma membrane. The cytoplasmic tail (AICD) contains the YENPTY motif for endocytic sorting, phosphorylation sites regulating protein interactions, and binding sites for adaptor proteins (Fe65, Mint1, Dab1).

Expression Pattern

APLP1 is highly expressed in the central nervous system with particularly high levels in the hippocampus (especially CA1 pyramidal neurons and dentate gyrus granule cells), cerebral cortex (layers II-IV and V-VI pyramidal neurons), cerebellum (Purkinje cells and granule cells), and olfactory bulb. In neurons, APLP1 localizes to synaptic vesicles and presynaptic terminals, postsynaptic densities, dendritic shafts and spines, and axonal growth cones during development.

Biological Functions

APLP1 plays critical roles in synapse formation and maturation. Studies show that APLP1-deficient mice exhibit reduced synaptic density in hippocampal neurons, impaired excitatory synaptic transmission, altered postsynaptic receptor clustering, and abnormal dendritic spine morphology. The extracellular domain of APLP1 mediates homophilic and heterophilic interactions with other APP family proteins, promoting synaptic adhesion and stabilizing synaptic contacts.

APLP1 is essential for long-term potentiation (LTP) and long-term depression (LTD), the cellular correlates of learning and memory. APLP1 interacts with NMDA receptor subunits (particularly GluN2B), modulating NMDA receptor function and is required for LTP induction in hippocampal CA1 neurons. APLP1-deficient mice show impaired spatial memory in Morris water maze tasks.

APLP1 also contains neuroprotective properties through multiple mechanisms including trophic support via the secreted ectodomain, activation of PI3K/Akt pathway promoting cell survival, calcium homeostasis modulation preventing excitotoxicity, and mitochondrial protection under stress conditions.

Role in Alzheimer's Disease

While APLP1 cannot produce Aβ peptides, it contributes to AD pathogenesis through amyloid-independent mechanisms. APLP1 loss-of-function disrupts synaptic plasticity and contributes to synaptic loss. The protein's role in NMDA receptor regulation means that APLP1 dysfunction could impair synaptic signaling, reduce activity-dependent plasticity, and accelerate synaptic degeneration.

APLP1 participates in cellular stress responses including oxidative stress where APLP1 expression is upregulated, ER stress involvement in the unfolded protein response, and mitochondrial dysfunction where APLP1 deficiency exacerbates damage.

Therapeutic Implications

Understanding APLP1's role in neurodegeneration opens potential therapeutic approaches including small molecules or peptides that boost APLP1 signaling, protein-protein interaction inhibitors blocking pathological interactions, and gene therapy restoring APLP1 expression in aging or diseased brains.

See Also

• [APP Gene](/genes/app)
• [APLP2 Gene](/genes/aplp2)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Amyloid Cascade Hypothesis](/mechanisms/amyloid-cascade)
• [Synaptic Plasticity](/mechanisms/synaptic-plasticity)

Brain Atlas Resources

• [Allen Human Brain Atlas](https://human.brain-map.org/) — gene expression data
• [BrainSpan Atlas](https://brainspan.org/) — developmental transcriptome
• [Allen Mouse Brain Atlas](https://mouse.brain-map.org/) — mouse brain gene expression

References

Pathway Diagram

The following diagram shows the key molecular relationships involving APLP1 Gene discovered through SciDEX knowledge graph analysis: