Tubulins are cytoskeletal proteins. α- and β-tubulin heterodimers polymerise to form microtubules, the roles of which include mechanical strength, intracellular trafficking and chromosome segregation. GTP molecules associated with β-tubulin molecules are hydrolyzed shortly after being incorporated into the polymerizing microtubules. GTP hydrolysis alters the conformation of the tubulin molecules and drives the dynamic behavior of microtubules. (Adapted from PMID:1121746 and PMID:25339962).