Taurine is Covalently Incorporated into Alpha Tubulin

We use various methods of high resolution mass spectrometry to demonstrate that taurine is covalently attached to the carboxyl terminus of alpha Tubulin from avian erythrocytes. The alpha Tubulin terminal residue, a tyrosine, must already be removed before covalent addition of taurine, via a known cycle of de-tyrosination and re-tyrosination. Taurination appears to stop this cycle. Taurine is the most abundant free amino acid in the body but this is the first time that it has been shown to be covalently incorporated into any protein.