Microtubules made from α-β tubulin heterodimers are important for cell migration, long range transport in cells, and cell division. The disordered C-terminal tails (CTT) are a primary site of tubulin regulation. Tubulin CTT affect microtubule (MT) length dynamics and mechanical properties, and are a major site of tubulin post-translational modification which regulates tubulin's binding interactions. Major questions remain about the molecular mechanism of tubulin CTT function and regulation. We have developed techniques to use nuclear magnetic resonance spectroscopy to study the binding and regulation by post-translational modification of the tubulin CTT. We find that the environment of the CTTs in the context of the full tubulin dimer is very different than that of isolated peptides, suggesting that the CTT dynamically interact with the ordered dimer surface in ways that can modify CTT and/or MT behavior, consistent with previous results showing that CTT affect MT polymerization and mechanical properties. Using this system we will study the the role of the CTTs in binding, and changes in CTT behavior as a result of post-translational modifications.