Mechanics of Centriole Microtubules

Abstract

This is a review paper describing recent findings about the physical properties of centriolar microtubules. Microtubules are the principal structures making up the centrioles. The centrioles in turn are the principal agents in cell duplication and division (mitosis). The microtubules are seen to be long hollow cylinders: approximately 400 nm in length, with a 24 nm outside diameter, and a 5 nm wall thickness. Within the centrioles, the microtubules are arranged into nine parallel sets of triplets—thus numbering 27 parallel cylinders per centriole. Each normal eukaryotic (human and animal) cell, not in mitosis, has two perpendicular centrioles connected at their proximal (base) ends. During mitosis, these two become four, resulting in a total of 108 centriolar microtubules. The structure of the microtubules themselves is found to consist of 13 parallel filaments making up the cylinder walls. The filaments are composed of approximately 40 and β -tubulin connected end-to-end with their proximal (base) ends anchored in γ -tubulin. The longitudinal vibrations of the filaments are believed to create an electro-magnetic field within the cell which plays an important role in mitosis.