The function of TTLL9 (tubulin tyrosine ligase like 9, Ensembl gene identifier ENSG00000131044) is as follows. Probable tubulin polyglutamylase that generates side chains of glutamate on the gamma-carboxyl group of specific glutamate residues within the C-terminal tail of target proteins. Similar to TTLL1, may acquire enzymatic activity only in complex with other proteins as it is most likely lacking domains important for autonomous activity. Mediates tubulin polyglutamylation which induces establishment of microtubule heterogeneity in sperm flagella, thereby playing a role in normal motile flagella axoneme structure and sperm flagella beating pattern. .