Core component of the 3M complex, a complex required to regulate microtubule dynamics and genome integrity. It is unclear how the 3M complex regulates microtubules, it could act by controlling the level of a microtubule stabilizer. Required for localization of CUL7 to the centrosome. Component of the 3M complex, composed of core components CUL7, CCDC8 and OBSL1. Interacts (via PxLPxI/L motif) with ANKRA2 (via ankyrin repeats); may link the 3M complex to histone deacetylases including HDAC4 and HDAC5. The PxLPxI/L motif mediates interaction with ankyrin repeats of ANKRA2. Despite its name, does not contain a coiled coil domain.