Regulator of the tubulin polyglutamylase complex (TPGC) that controls cytoskeletal organization, nuclear shape, and cilium disassembly by balancing microtubule and actin assembly (PubMed:34782749). Regulates the assembly and stability of the TPGC and thereby modulates polyglutamylation of the microtubule, which antagonizes MAP4 binding (PubMed:34782749).