DIVERSE DISTRIBUTION AND FUNCTION OF FIBROUS MICROTUBULE-ASSOCIATED PROTEINS IN THE NERVOUS-SYSTEM

This chapter highlights the cellular and subcellular distribution of fibrous microtubule-associated proteins (MAPs) in the vertebrate nervous system. It emphasizes on the functional roles of various fibrous MAPs in nervous tissues such as the establishment and maintenance of cellular form, the differentiation of particular types of neuronal and supporting cells in diverse regions of the nervous system, and the generation and regulation of the outgrowth, plasticity, and stabilization of neuronal processes. MAPs are nontubulin proteins which copurify to constant stoichiometry with tubulin either during cycles of temperature-dependent microtubule assembly and disassembly or during taxol-stimulated microtubule assembly. The major categories of nervous tissue MAPs according to the molecular mass of the principal subunits include: high molecular mass (HMM), intermediate molecular mass (IMM), and low molecular mass (LMM). A role for MAPs in the establishment and regulation of neuronal form is inferred from their varied, but specific associations with the three principal structural compartments or domains of neurons—namely, axonal, somatic, and dendritic. Antibodies to some MAPs are frequently used as compartment-specific markers, although there is evidence that all major MAPs are expressed in all three compartments under some circumstances. © 1994 Academic Press, Inc.