The interaction between KIF4A and condensin I.
(A) HeLa cells expressing EGFP-KIF4A WT or S1186 were arrested at mitosis and the KIF4A-condensin I complex was recovered by immunoprecipitation against GFP and SMC2. Mitotic extracts prepared from no EGFP expressing cells (-) were also analyzed as a negative control. To detect KIF4A and condensin, the anti-GFP, -CAPD-2, -CAP-D3, and -SMC2 antibodies were used for WB analysis. (B) A model of the chromosome organization by KIF4A phosphorylation. In interphase, KIF4A and condensin I localize in the nucleus and cytoplasm, respectively. In early mitosis, KIF4A is phosphorylated at S1186 by Cdk1, and associates with the chromosome. After NEB, condensin I is also distributed to the chromosome. KIF4A and condensin I then would form a complex in the chromosome by their further phosphorylation by aurora B. KIF4A assists in the accumulation of condensin I in the chromosome scaffold using its motor activity, and lateral chromatid compaction is achieved.