Required for spindle microtubule attachment to both kinetochores and centrosomes. Also functions to tether minus-ends of spindle microtubules to centrosomes. May act by forming ring-like structures around microtubules, or by serving as a cross-linker or scaffold at the attachment site. Interacts with clip1, mis12, ndc80 and zwint. Interacts with gamma-tubulin. Localizes to spindle microtubules. Belongs to the translokin family.