Microtubules by Jessica Belliveau

Introduction

Microtubules, along with actin and intermediate filaments, compose the cytoskeleton of eukaryotic cell. Microtubules are involved with mitosis, cell movement, intracellular transport, and cell structure. Microtubules (MT) are made up of the globular protein, tubulin. The two main forms of tubulin found in MT are α-tubulin and β-tubulin. α-tubulin and β-tubulin spontaneously bind to form a dimer and many tubulin dimers form together into protofilaments. The protofilaments assemble into MT. Microtubules are polar structures with a fast-growing positive end and a slow-growing negative end.

Figure 1. A. The microtubule is in dynamic instability with consistent growing and shrinking. B. The cycle of growth (polymerization) and shrinking (depolymerization)