Polyglycylase which modifies both tubulin and non-tubulin proteins, generating side chains of glycine on the gamma-carboxyl groups of specific glutamate residues of target proteins. Polyglycylates alpha-tubulin and beta-tubulin, but is not able to initiate glycylation and only has activity toward monoglycylated tubulin. Has the ability to polyglycylate non-tubulin proteins such as NAP1, in this case it can initiate glycylation and does not require preliminary monoglycylation by another glycylase.