tyrosinated

Tyrosinated refers to the post-translational modification state of alpha-tubulin in microtubules in which a C-terminal tyrosine residue is present. It is part of a reversible tyrosination–detyrosination cycle that modulates microtubule properties. The tyrosine is added to detyrosinated alpha-tubulin by tubulin tyrosine ligase (TTL). Detyrosination, the removal of the C-terminal tyrosine, is performed by tubulin carboxypeptidases, generating detyrosinated tubulin; TTL can re-add tyrosine to restore the tyrosinated form. In some cases, tubulin can undergo further processing to delta2-tubulin, a more extensively detyrosinated species.

Tyrosinated microtubules tend to be more dynamic, enriched at growing plus ends, and often associated with active remodeling, whereas detyrosinated microtubules are generally more stable and longer-lived. The tyrosination state affects the binding of specific microtubule-associated proteins and motor proteins, influencing intracellular transport, cell polarity, and neuronal development.

Biological and clinical relevance: Alterations in the tyrosination cycle have been studied as markers of microtubule turnover in cells and have been investigated in the contexts of cancer and neurodegenerative disorders, where changes in microtubule dynamics may impact cell behavior.

See also: tubulin tyrosine ligase, tubulin carboxypeptidases, microtubule modification.