Final answer:
The Nissl body is the part of a neuron that is directly involved with protein synthesis.
Step-by-step explanation:
The part of a neuron that is directly involved with protein synthesis is the Nissl body. Nissl bodies, also known as Nissl substances or chromophilic substances, are clusters of rough endoplasmic reticulum found in the cell body of a neuron. They play a key role in producing proteins that are necessary for the function and maintenance of the neuron.