Tubulin Tyrosine Ligase Like Protein 13 (TTLL13)

TTLL13 is a member of a family of proteins that are related to tubulin tyrosine ligase, an enzyme that ligates tyrosine onto the carboxy-terminal tails of tubulins. GTRGEO22 was recently identified as being a component of a mu1ti-protein complex having tubulin polyglutamylasc (TPG) activity. This led to the hypotheses that TTLL13 is a catalytic subunit of TPG and that ROSA22 homozygous mice have abnormal tubulin polyglutamylation. To test the latter hypothesis, brain and testis protein extracts from ROSA22 mutant mice were analyzed using SDS-PAGE and western blotting. This revealed a change in the polyglutamylation of tubulin. Analysis of the protein sequence of specific TTLLs has revealed a potential GTRGEO22 interaction domain that is conserved in several species. These results are consistent with a model where GTRGEO22 localizes TTLL13 to tubulin where they act as polyglutamylases.