The key difference between slow and fast axonal transport is that slow axonal transport is the mechanism that transports cytoskeleton components at a rate of less than 8 mm per day, while fast axonal transport is the mechanism that transports cytoskeleton components at a rate of 200-400 mm per day or 2-5μm per second.
Axonal transport is a cellular process that is responsible for the movement of different organelles and molecules along an axon of a neuron. It is also known as axoplasmic transport or axoplasmic flow. The two types of axonal transport are slow axonal transport and fast axonal transport.
CONTENTS
1. Overview and Key Difference
2. What is Slow Axonal Transport
3. What is Fast Axonal Transport
4. Similarities – Slow and Fast Axonal Transport
5. Slow vs Fast Axonal Transport in Tabular Form
6. Summary – Slow vs Fast Axonal Transport
What is Slow Axonal Transport?
Slow axonal transport is the slow transport of cytoskeleton polymers and cytosolic protein complexes along axons of neurons at a rate of less than 8mm per day. Advanced imaging techniques have led to the understanding of the slow axonal transport mechanism in recent years. These imaging techniques include fluorescent labelling techniques such as fluorescence microscopy.
Figure 01: Axonal Transport
The cytoskeleton components in the axonal transport mechanism take a longer time to move along the length of the axon. It has been now discovered that slow axonal transport actually occurs rapidly, but due to frequent pausing, the overall transit rate becomes much slower. This mode of transport is referred to as the ‘Stop and Go’ model. This model extensively validates the transport of cytoskeleton protein neurofilament. The movement of cytosolic proteins in slow axonal transport occurs in a complex form.
What is Fast Axonal Transport?
Fast axonal transport is the fast movement of membrane vesicles and the relative content over long distances of an axon within a neuron at a rate of 200-400mm per day or 2-5μm per second. During initial biochemical and morphological studies, it was evident that materials moving in fast axonal transport involved membrane-bound organelles. These materials include mitochondria, membrane-associated receptors, proteins, neurotransmitters, synaptic vesicles, and neuropeptides. The size of the material or membrane-bound organelle directly affects the rate of transport.
Small membrane-bound materials tend to move fast, and organelles such as mitochondria move relatively slow. The basic principle for fast axonal transport was understood decades ago. Fast axonal transport provides a rapid supply of freshly synthesized components essential for the maintenance and function of the neuronal membrane.
What are the Similarities Between Slow and Fast Axonal Transport?
- Slow and fast axonal transport are transport mechanisms that take place within the neuron.
- Both mechanisms transport materials along the length of the axon.
- They efficiently deliver materials that cannot be transported through diffusion.
What is the Difference Between Slow and Fast Axonal Transport?
Slow axonal transport is the transportation of cytoskeleton components at a rate of less than 8mm per day, while fast axonal transport is the transportation of cytoskeleton components at a rate of 200-400mm per day or 2-5μm per second. Thus, this is the key difference between slow and fast axonal transport. Moreover, slow axonal transports carry cytoskeleton polymers and protein complexes, while fast axonal transports carry mitochondria, membrane-associated receptors, neurotransmitters proteins, and synaptic vesicles.
The below infographic presents the differences between slow and fast axonal transport in tabular form for side by side comparison.
Summary – Slow vs Fast Axonal Transport
Axonal transport is a cellular process that is responsible for the movement of different organelles and molecules along an axon of a neuron. Slow axonal transport occurs at slower rates, while fast axonal transport occurs at rapid rates during the transport of materials along the axon of a neuron. The cytoskeleton components in the slow axonal transport take place at a rate of less than 8mm per day. During fast axonal transport, materials move at a rate of 200-400mm per day or 2-5μm per second. Moreover, slow axonal transports carry cytoskeleton polymers and protein complexes, while fast axonal transports carry mitochondria, membrane-associated receptors, neurotransmitters proteins, and synaptic vesicles. So, this summarizes the difference between slow and fast axonal transport.
Reference:
1. “Fast Axonal Transport.” An Overview | ScienceDirect Topics.
2. “Slow Axonal Transport Latest Research Papers.” ScienceGate.
Image Courtesy:
1. “Cytoplasmic dynein” By User:Delldot – Own work (CC BY 3.0) via Commons Wikimedia