Microtubule-binding protein essential for faithful chromosome segregation. Mediates TRF1 and TERT accumulation in nucleolus and enhances TRF1 binding to telomeres. Inhibits telomerase activity. May inhibit cell proliferation and act as tumor suppressor (By similarity). Interacts with MCRS1, TERT, TERF1, NCL/nucleolin, and the telomerase RNA. Localizes in nucleoli, at telomere speckles and to the outer plate of kinetochores. Localization to the kinetochore is mediated by its central region and depends on NDC80 and CENPE (By similarity). The TID (telomerase inhibiting domain) domain is sufficient to bind TERT and inhibits its activity. The TBM domain mediates interaction with TERF1. Belongs to the PINX1 family.