The Structure of Microtubules - A Brief History

The first images of tubulin within the cell began to be observed in the 1950s and 1960s via transmission electron microscopy⁽¹⁾. However, initial fixation methods at that time did not preserve the tubulin structure for it to be observed consistently. Initially, scientists thought these tubulin structures were canaliculi, endoplasmic reticulum, or filamentous elements^(2,3). In 1963, after the development of using glutaraldehyde as a fixative, the consistency and resolution of tubulin improved, and the term “microtubules” (MTs) was introduced^(4-6). Several years later, Gary Borisy and Ed Taylor at the University of Chicago used tritium-labeled colchicine as a small molecule probe to elucidate how colchicine inhibited mitosis. They discovered that a structural protein must be binding the labeled colchicine, as it was taken up by KB and Hela cells in tissue culture⁽⁷⁾, sea urchin eggs⁽⁸⁾, sea urchin sperm tails⁽⁹⁾, and the brain⁽¹⁰⁾. Soon after, Hideo Mohri gave the colchicine-binding protein the official name of tubulin⁽¹¹⁾. Interest in microtubules increased, as these cylindrical polymer structures were recognized as essential components of the cytoskeleton required for cell growth and maintaining cell shape⁽¹²⁾.