Abstract：Microtubules， composed of alpha/beta tubulin dimer ， are the basic components of eukaryotic cytoskeleton.
Its dimeric structure is highly conserved evolutionarily， yet can assume multiple functions， mainly because its
structure and properties can be regulated by multiple mechanisms， especially post-translational modifications
of tubulin. Several post-translational modifications of tubulin have been identified， among which glycylation is
an important modification， which is modified with glutamylation at the C-terminal glutamate residue of tubulin.
However， unlike glutamylation， glycine is a neutral amino acid and does not increase the net negative charge of
the C-terminus of tubulin. This modification is mainly catalyzed by the tubulin tyrosin ligase-like（TTLL） enzyme
family， where the enzymes that play an important role in the initiation of glycylation are TTLL3 and TTLL8， and
the enzyme that plays an important role in the extension process is TTLL10. This post-translational modification
can improve the stability of microtubules by changing the spatial conformation of the C-terminus of tubulin， which
in turn changes the radius of rotation and binding structure of the C-terminus， thus maintaining the structural
stability and normal function of cilia. In the central nervous system， glycylation has a competitive inhibitory effect
on glutamylation， which may be one of the protective mechanisms for neurodegenerative changes. In the retina，
inhibition of microtubule protein glycylation in mice leads to a decrease in the number of attached cilia， resulting in
degenerative retinal changes. In the development of colorectal cancer， inhibition of glycylation increases the risk of
colorectal cancer development. In spermatozoa， inhibition of glycylation impedes linear swimming of spermatozoa，
leading to male sterility. The function of tubulin glycylation and its regulatory mechanism in other tissues or life
activities where tubulin post-translational modifications are abundant， such as platelets， myocytes， and cell mitosis，
remain to be studied in depth.