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Updated: Mar 27, 2026

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
CDK1-dependent N-terminal NuMA phosphorylation promotes dynein-dynactin-NuMA assembly for accurate chromosome
Marvin van Toorn1, Merve Aslan2, Keishi Shintomi3
1Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan.
Abstract:
The microtubule-based motor dynein and its cofactor dynactin are activated by various adaptors to fulfill essential functions throughout the cell cycle, including organelle transport and mitotic spindle assembly. NuMA is a mitotic adaptor that interacts with dynein-dynactin via its N-terminal region (NuMA-N). However, how NuMA-N binds and activates dynein-dynactin in mitosis remains unclear. Here, we combine a membrane-tethering assay, quantitative proteomics, and live-cell analyses to show that mitotic phosphorylation of NuMA-N drives dynein-dynactin-NuMA (DDN) assembly. We find that CDK1-Cyclin B1 phosphorylates NuMA-N, primarily at its conserved serine 203, which stimulates dynein activation in vitro. Replacing endogenous NuMA with phosphorylation-deficient mutants further reveals that NuMA-N phosphorylation, together with its dynein-binding site and Spindly-like motif, is required to form stable DDN complexes for functional spindle assembly. These results highlight CDK1-dependent N-terminal NuMA phosphorylation as a crucial mitotic phospho-switch that ensures stable multivalent interactions between dynein-dynactin and NuMA for accurate chromosome segregation.
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