ADAM23 Protein
Overview
ADAM23 (A Disintegrin And Metallopeptidase Domain 23) is a transmembrane metalloprotease belonging to the ADAM family of proteins, a group of proteolytic enzymes characterized by their distinctive domain architecture. The human ADAM23 protein is encoded by the ADAM23 gene located on chromosome 11 and consists of approximately 749 amino acids with a predicted molecular weight of ~100 kDa. As a type I transmembrane protein, ADAM23 is anchored at the cell membrane with its catalytic domain oriented extracellularly, positioning it to interact with both membrane-bound and extracellular substrates. The protein exhibits particularly enriched expression in the nervous system, especially in neuronal populations and brain tissue, making it a key player in neurobiological processes relevant to neurodegeneration research.
Function and Biology
ADAM23 functions primarily as a sheddase—an enzyme that proteolytically cleaves and releases extracellular portions of membrane proteins. The protein contains a characteristic metallopeptidase domain with a zinc-binding site essential for catalytic activity, along with disintegrin and cysteine-rich domains that mediate protein-protein interactions. Beyond its proteolytic function, ADAM23 serves as a cell adhesion molecule through interactions between its disintegrin domain and integrin receptors on adjacent cells. This dual functionality makes ADAM23 involved in both cell-cell communication and substrate processing.
...ADAM23 Protein
Overview
ADAM23 (A Disintegrin And Metallopeptidase Domain 23) is a transmembrane metalloprotease belonging to the ADAM family of proteins, a group of proteolytic enzymes characterized by their distinctive domain architecture. The human ADAM23 protein is encoded by the ADAM23 gene located on chromosome 11 and consists of approximately 749 amino acids with a predicted molecular weight of ~100 kDa. As a type I transmembrane protein, ADAM23 is anchored at the cell membrane with its catalytic domain oriented extracellularly, positioning it to interact with both membrane-bound and extracellular substrates. The protein exhibits particularly enriched expression in the nervous system, especially in neuronal populations and brain tissue, making it a key player in neurobiological processes relevant to neurodegeneration research.
Function and Biology
ADAM23 functions primarily as a sheddase—an enzyme that proteolytically cleaves and releases extracellular portions of membrane proteins. The protein contains a characteristic metallopeptidase domain with a zinc-binding site essential for catalytic activity, along with disintegrin and cysteine-rich domains that mediate protein-protein interactions. Beyond its proteolytic function, ADAM23 serves as a cell adhesion molecule through interactions between its disintegrin domain and integrin receptors on adjacent cells. This dual functionality makes ADAM23 involved in both cell-cell communication and substrate processing.
ADAM23 interacts with various ligands and substrates at the neuronal membrane, including cadherins, protocadherins, and other adhesion molecules critical for synaptic function and plasticity. The protein is particularly important in synaptogenesis and synaptic maintenance, processes that depend on dynamic regulation of cell adhesion molecules and extracellular matrix components. ADAM23 expression and localization are developmentally regulated, with elevated levels during periods of active synapse formation and remodeling.
Role in Neurodegeneration
ADAM23 has emerged as a significant player in several neurodegenerative disease contexts. Research has identified altered ADAM23 expression and function in Alzheimer's disease pathology, where aberrant proteolytic activity contributes to amyloid-beta generation and tau metabolism. The enzyme's ability to process amyloid precursor protein (APP) and related substrates positions it at the intersection of pathogenic pathways in Alzheimer's disease. Additionally, genetic variations in ADAM23 have been associated with increased susceptibility to Parkinson's disease, suggesting its involvement in neuronal survival and dopaminergic system integrity.
In amyotrophic lateral sclerosis (ALS) and frontotemporal dementia contexts, ADAM23 dysregulation may contribute to progressive motor neuron loss through alterations in cell-cell adhesion and synaptic stability. The protein's role in maintaining synaptic architecture and preventing excitotoxicity makes its dysfunction potentially relevant to multiple neurodegenerative conditions characterized by progressive neuronal loss.
Molecular Mechanisms
ADAM23-mediated neurodegeneration operates through several interconnected mechanisms. First, dysregulated shedding of cell adhesion molecules compromises synaptic stability and neuronal connectivity. Second, altered substrate processing affects the availability of neurotrophic factors and axon guidance molecules essential for neuronal survival. Third, ADAM23 dysfunction influences inflammatory signaling through its ability to process cytokine precursors and adhesion molecules involved in immune cell recruitment to the nervous system.
The protein's catalytic activity is regulated by endogenous inhibitors including tissue inhibitors of metalloproteinases (TIMPs), and dysregulation of this balance contributes to pathological proteolysis in neurodegeneration. Transcriptional and post-translational modifications of ADAM23 are influenced by oxidative stress and neuroinflammatory signals characteristic of neurodegenerative diseases.
Clinical and Research Significance
ADAM23 represents an important biomarker and therapeutic target in neurodegeneration research. Genetic association studies have linked ADAM23 polymorphisms to Parkinson's disease risk through genome-wide association studies. Proteomic analyses reveal altered ADAM23 expression in cerebrospinal fluid and brain tissue from patients with Alzheimer's disease and other dementias, suggesting potential diagnostic utility. Mechanistic studies investigating ADAM23 inhibition as a therapeutic strategy are underway for conditions where excessive proteolysis contributes to pathology.
- ADAM10: A closely related protease with overlapping substrate specificity and neurobiological functions
- ADAM17: Another ADAM family member involved in TNF-alpha processing and neuroinflammation
- Amyloid Precursor Protein (APP): A primary ADAM23 substrate relevant to Alzheimer's disease
- Cell Adhesion Molecules: Key substrates including L1-CAM and cadherins
- TIMPs: Endogenous regulatory proteins controlling ADAM23 activity
AlphaFold Structure
AlphaFold DB provides a predicted structure for ADAM23 / UniProt O75077 (model version 6): https://alphafold.ebi.ac.uk/entry/O75077.
AlphaFold reports a mean pLDDT confidence score of 76.12, indicating confident backbone placement for much of the model, with lower-confidence regions possible.
InterPro annotations highlight EGF-like domain domain (732-769); Peptidase M12B, ADAM/reprolysin domain (299-496); Disintegrin domain domain (502-588).
PDB coordinates: https://alphafold.ebi.ac.uk/files/AF-O75077-F1-model_v6.pdb mmCIF coordinates: https://alphafold.ebi.ac.uk/files/AF-O75077-F1-model_v6.cif.
Use the prediction as structural context for target assessment; local low-pLDDT segments may reflect disorder, flexible linkers, or unresolved domain orientation rather than a stable fold.