Final answer:
Cytoplasmic dynein is the motor protein responsible for retrograde axonal transport, moving cellular components from the nerve endings back towards the neuron cell body along the microtubules of the axon.
Step-by-step explanation:
The motor protein responsible for retrograde axonal transport is cytoplasmic dynein. Retrograde transport refers to the movement of organelles and vesicles containing molecules such as neurotransmitters, back from the nerve endings to the cell body along axons. While kinesin motor proteins are typically associated with anterograde transport, moving cargo away from the cell body to the axon terminal, dynein moves in the opposite direction. This retrograde movement is essential for the recycling of synaptic vesicles and other cellular components, and also for the delivery of signals from the synapse back to the cell body.
Powered by the hydrolysis of ATP, dynein associates with microtubules within the axon and moves cargo towards the minus-end of the microtubule, which is generally oriented towards the cell body (centrosome). This process is crucial for maintaining the health and function of neurons since it enables the recycling and replenishment of vesicles that contain neurotransmitters and other necessary cellular constituents.