ABSTRACT
The subcellular transport of substances throughout the neuron facilitates neuronal functioning. A simple example of this is the transport of mRNA from the nucleus to the cytoplasm where translation takes place. These proteins function in various cellular regions depending on their cellular function. At least one class of these proteins, called transcription factors, is transported back into the nucleus where it alters the transcription rates of various genes. A more specialized function for protein transport arises from the functional polarity of a neuron. Neurons receive information about their cellular environment through their dendrites. This information is transduced into a cellular response in the cell body which in turn may be propagated to the next cell via signaling through the axon to the next postsynaptic neuron. This functional polarity results in part from protein transport as demonstrated by the ionotropic glutamate receptors which are translated in the cell body, transported to dendrites, and bind glutamate, which is secreted from the presynaptic neuron. This functional polarity is paralleled in the morphological polarity of neurons where a single neuron usually has multiple dendrites but only one axon.
