Tubulin Tyrosine Ligase Like Protein 9 (TTLL9)

TTLL9 is a member of a large family of proteins with a TTL homology domain, whose members could catalyze ligations of diverse amino acids to tubulins or other substrates. TTLL9 is closely related evolutionarily to TTLL1. However, attempts to detect glutamylation activities associated with mammalian TTLL1 and TTLL9 expressed either in mammalian cells or in Escherichia coli were not successful. The TTLL9 knockout cells did not change the pattern of glutamylation seen in immunofluorescence. Based on Western blot assays, loss of TTLL1 alone reduced the levels of ID5 epitopes in the whole cytoskeletons and loss of TTLL9 alone reduced the levels of ID5-reactive tubulins in cilia, primarily in the faster-migrating portion of the tubulin region that is enriched in tubulin.