Control of microtubule polymerization and stability

Abstract

Microtubules are protein polymers that, together with microfilaments and intermediate filaments, constitute the cytoskeleton. They are involved in essential cell functions including the regulation of cell shape, movement, division and intracellular organelle transport and organization. Microtubule protein composition has been determined after the isolation of microtubules by a procedure that consists of cycles of in vitro temperature-dependent assembly and disassembly of the polymers. The major component of isolated microtubules is a protein called “tubulin.” The study of the structural and functional domains of tubulin has been performed using several approaches. One of these takes advantage of the structural homology between certain proteins with similar functional features and of the existence of several empirical methods to predict the secondary structure of a protein from its primary sequence. These tubulin-binding proteins were originally referred to as “microtubule-associated proteins” (MAPs) and have the ability to promote the polymerization of tubulin into microtubules. Microtubule nucleation, elongation, and stabilization may be controlled by specific microtubule-associated proteins (MAP). Factors other than MAPs that influence microtubule organization and dynamics include several microtubule-binding proteins (MTBP), as well as certain organelles, such as the microtubule organizing centers (MTOC). © 1995 Elsevier Inc.