Centralspindlin is a motor complex implicated in cell division. It contributes to virtually every step in cytokinesis, [1] It is highly conserved in animal cells as a component of the spindle midzone and midbody. [2] Centralspindlin is required for the assembly of the mitotic spindle [3] as well as for microtubule bundling and anchoring of midbody microtubules to the plasma membrane. [1] [2] This complex is also implicated in tethering the spindle apparatus to the plasma membrane during cytokinesis [4] This interaction permits cleavage furrow ingression. In addition, centralspindlin's interaction with the ESCRT III allows for abscission to occur. [1]
Centralspindlin is a heterotetramer consisting of two different subunit proteins: [1]
Both KIF23 and RacGAP1 dimerize via their parallel coiled coil domain. [2] [5] Centralspindlin oligomerizes in order to link the mitotic spindle with the plasma membrane [1] The sequences mediating interactions between KIF23 and RacGAP1 are highly variable between species. However, a high affinity interaction between these subunits is essential for the proper functioning of the Centralspindlin complex. [5]
KIF23 interacts with microtubules at sites of overlap, [2] linking the centralspindlin complex to the mitotic spindle. RacGAP1 recruits ECT2 to the central spindle. [3] ECT2 is a Guanine nucleotide-exchange factor for RhoA. Cytokinesis is initiated when RhoA is activated by ECT2. [6] RacGAP1 is also involved in tethering the central spindle to the plasma membrane. Without this interaction, cytokinesis cannot occur. [4]