sentrosomin

Centrosomin is a centrosomal protein in Drosophila melanogaster essential for centrosome maturation and mitotic spindle assembly. The protein localizes to the centrosome and the pericentriolar material (PCM) throughout the cell cycle, with enrichment during mitosis.

Centrosomin is a large coiled-coil protein encoded by the cnn gene. It contains motifs including the conserved CM1 motif that mediates binding to the gamma-tubulin ring complex (gamma-TuRC) and promotes recruitment of gamma-tubulin to the centrosome, thereby facilitating microtubule nucleation at the PCM.

Functionally, Centrosomin promotes microtubule nucleation at the centrosome and is required for proper spindle formation. Loss of cnn results in defects in spindle poles, abnormal spindle morphology, chromosome mis-segregation, and early embryonic lethality, reflecting its critical role in mitotic fidelity.

Regulation of Centrosomin involves cell cycle-dependent control, with mitotic kinases modulating its recruitment to the PCM and promoting PCM expansion to support robust spindle assembly during mitosis.

Centrosomin is conserved in other organisms, where related proteins participate in PCM organization and microtubule nucleation. In mammals, functional analogs such as CEP215/CDK5RAP2 mediate similar roles in centrosome maturation and gamma-tubulin tethering, indicating a preserved core function across species.

Overall, Centrosomin is a core PCM component that coordinates centrosome maturation and spindle assembly by concentrating gamma-tubulin at the centrosome and enabling efficient microtubule nucleation during cell division.