Tubulin synthesis and assembly in differentiating neurons.

Neurons are highly polarized cells that extend long processes, the axons and dendrites, to form contacts with target cells. The formation and maintenance of this specialized morphology relies on the assembly of an organized microtubule array that is the predominant component of the neuronal cytoskeleton. During this process there is an evolution in the composition and dynamics of microtubules, resulting in stable microtubule bundles that provide structural support and function in intracellular transport along the axon. In this essay we provide an overview of the mechanisms regulating the synthesis and assembly of tubulin in differentiating neurons with particular attention to the roles of multiple tubulin isotypes, posttranslational modifications of tubulin, and microtubule-associated proteins. We conclude that, ultimately, the developmental regulation of microtubules in neurons may require the coordinated expression and posttranslational modifications of tubulin and microtubule-associated proteins to provide biochemical forms that favour specific interactions, each combination conferring distinctive dynamic and functional properties.