Clathrin is a major protein component of the vesicle coat that mediates receptor-mediated endocytosis and intracellular membrane trafficking[^1]. In neurons, clathrin-mediated endocytosis is essential for synaptic vesicle recycling, a process critical for sustained neurotransmitter release at synapses[^2].
The clathrin heavy chain (CLTC) gene encodes a protein of 1,675 amino acids that assembles into a triskelion structure. Each clathrin triskelion consists of three heavy chains and three light chains, forming the characteristic three-legged structure that can polymerize into clathrin-coated vesicles[^3].
Clathrin has a complex multi-domain structure:
¶ Terminal Domain
The N-terminal terminal domain contains:
- Seven-bladed beta-propeller structure
- Binding sites for accessory proteins
- Linker region connecting to the ankle
¶ Ankle Domain
The ankle region forms:
- Extended helical structures
- Trimerization interface
- Flexibility for coat assembly
¶ Leg Domain
The leg (proximal and distal domains):
- Alpha-solenoid repeat structures
- Flexible, elongated structure
- Forms the bulk of the clathrin lattice
Light chains (CLTA and CLTB):
- Bind to the leg domain
- Regulate clathrin assembly
- Link to the actin cytoskeleton[^4]
Clathrin mediates receptor-mediated endocytosis:
- Formation of clathrin-coated pits
- Cargo selection and concentration
- Vesicle scission and uncoating
In neurons, clathrin is essential for:
- Recycling synaptic vesicles after release
- Clearing synaptic membrane components
- Maintaining the synaptic vesicle pool
Beyond the plasma membrane, clathrin:
- Forms vesicles at the Golgi apparatus
- Mediates trafficking between endosomes
- Participates in lysosomal targeting[^5]
Clathrin-mediated endocytosis is implicated in AD:
- Amyloid precursor protein (APP) internalization
- Amyloid-beta generation through endocytic pathway
- Amyloid-beta effects on clathrin function
In PD:
- Dopamine receptor trafficking requires clathrin
- Alpha-synuclein affects endocytic pathways
- LRRK2 mutations alter endocytosis
In motor neuron disease:
- Mutant SOD1 affects endocytic trafficking
- Disrupted synaptic vesicle recycling
- Axonal transport deficits[^6]
Therapeutic strategies include:
- Endocytosis inhibitors: Modulate APP processing
- Synaptic function enhancers: Improve vesicle recycling
- Targeted drug delivery: Use clathrin for CNS drug delivery
- Vesicle trafficking modulators: Restore proper trafficking[^7]
- Pearse & Robinson, Clathrin in endocytosis (1984)
- Kirchhausen, Clathrin structure (2000)
- Dannhauser & Hieter, Clathrin in neurodegeneration (2020)
- Wu et al., Clathrin and synaptic function (2019)
- Brodsky et al., Clathrin-coat assembly in vesicle trafficking (2001)
- Dannhauser et al., Effect of clathrin light chain depletion on synaptic function (2017)
- McMahon et al., Molecular mechanisms of clathrin-mediated endocytosis (2008)
- Boehm et al., Clathrin-mediated endocytosis in neuronal cells (2005)
- Park et al., Clathrin adaptors in neurodegenerative disease (2013)
- Wakeham et al., The role of clathrin in synaptic vesicle recycling (2000)