Negatively regulates post-translational modifications of tubulin, including detyrosination of the C-terminus and polyglutamylation of glutamate residues (PubMed:20162578, PubMed:23251473). Also, indirectly promotes histone H4 trimethylation at 'Lys-20' (H4K20me3) (PubMed:23251473). Probably by controlling tubulin and/or histone H4 post-translational modifications, plays a role in mitosis and in maintaining chromosome number stability (PubMed:20162578, PubMed:23251473). During RNA virus-mediated infection, acts as a negative regulator of the RIG-I pathway by preventing MAVS binding to TBK1 and IKBKE (PubMed:28011935). {ECO:0000269|PubMed:20162578, ECO:0000269|PubMed:23251473, ECO:0000269|PubMed:28011935}. This is the function of TTLL12 (tubulin tyrosine ligase like 12, ENSG00000100304).