Schematic representation of the KIF14 protein (not to scale). KIF14 contains two major effector domains. The first is a highly conserved 274 aa kinesin motor domain containing an ATP-binding site (aa 447-454) which is involved in microtubule-dependent ATPase activity, and a microtubule binding site (aa 455-628) involved in ATP-dependent protein transport. The second is a 67 aa forkhead-associated (FHA) domain (aa 825-891) which has similarity to the SMAD Mad Homology 2 (MH2) domain, and is involved in mediating protein-protein interactions with phosphoproteins, although no such interactions have been documented for KIF14 (Durocher et al., 2000). In addition to the highly conserved N-type neck region (N) adjacent to the motor domain, KIF14 also contains four other C-terminal regions predicted to form coiled-coil structures (1-4). Phosphorylation sites have been identified in high-throughput studies on Ser-12, Tyr-196, Thr-240, Ser-242, Ser-378, Ser-384, Ser-670, Ser-1200, Ser-1292, Ser-1631, Ser-1636 and Thr-1641 (P) (Nomura et al., 1994; Olsen et al., 2006; Vasilescu et al., 2007; Dephoure et al., 2008), and a ubiquitination site identified on Lys-275 (U) (Olsen et al., 2006; Vasilescu et al., 2007). The kinesin motor and FHA domains are flanked by a 354 aa N-terminal extension, and a 758 aa C-terminal stalk and tail region. The N-terminal extension is involved in the binding of PRC1 (protein-regulating cytokinesis 1), a protein crucial for the proper formation of the central spindle structure during cytokinesis. Citron kinase has been shown to interact with the C-terminal stalk and tail of KIF14, and this interaction is required for proper localization of KIF14 to the mitotic spindle. Supervillin, a membrane protein involved in directing cellular motility, has been shown to associate directly with the distal C-terminal tail of KIF14 and contributes to the establishment or maintenance of the cytokinetic furrow (Smith et al., 2010).