TTL (tubulin tyrosine ligase) ligates tyrosine (L-Tyr) to the carboxy terminus of the alpha-tubulin subunit of an alpha tubulin:beta tubulin dimer in an ATP-dependent reaction. Human TTL has not been characterized in detail; the reaction mechanism annotated here has been worked out with bovine proteins (Deans et al. 1992), and structural studies with chicken proteins demonstrate the basis of the enzyme's specificity for the carboxy terminus of tubulin alpha chains (Prota et al. 2013).
tubulin-tyrosine ligase activity of TTL [cytosol]