TTCP (tubulinyl-tyrosine carboxypeptidase) hydrolyzes the terminal L-Tyr residue from the alpha-tubulin subunit of an alpha tubulin:beta tubulin dimer to yield delY-alpha tubulin and L-tyrosine (L-Tyr). Although TTCP enzyme has not been purified from any species, studies of material partially purified from chicken brain have allowed its activity to be defined and distinguished from those of widely expressed carboxypeptidases with broader substrate specificities (Argarana et al. 1980). This reaction is known to occur in humans (Song & Brody 2015; Yu et al. 2015) and its properties have been inferred from those of its chicken counterpart.