MCAK, a Kin I kinesin, increases the catastrophe frequency of steady‐state HeLa cell microtubules in an ATP‐dependent manner in vitro

Abstract

Mitotic-centromere-associated kinesin (MCAK) is a member of the KIN I (internal motor domain) subfamily of kinesin related proteins. MCAK and its homologues destabilize microtubules both in cells and in vitro. Here, we analyzed the effects of MCAK in the presence and absence of ATP on the dynamic instability behavior of steady state microtubules assembled from purified HeLa cell tubulin. In the presence of ATP, substoichiometric levels of full length MCAK and a segment (A182) consisting of the motor and neck domains strongly increased the catastrophe frequency of the microtubules. These data demonstrate that MCAK is a microtubule-catastrophe promoting factor in vitro, and support the hypothesis that MCAK may serve as a catastrophe-promoting factor in cells.

Mid-anaphase arrest in S. cerevisiae cells eliminated for the function of Cin8 and dynein

“…In the first, both motors directly associate with MTs at the midzone and their absence therefore disrupts midzone organization. Previous reports regarding the functions of kinesin-related motor proteins in midzone and spindle MT organization [19,[60][61][62][63][64] as well as in control of MT dynamics [65][66][67][68][69] support this idea. In addition, we have recently reported that a combination of mutations in kinesin-5 motors disrupts midzone organization and centering [42].…”

The C-termini of tubulin and the specific geometry of tubulin substrates influence the depolymerization activity of MCAK

“…[9][10][11] MCAK, the most studied Kinesin-13, can depolymerize stabilized MTs as well as dynamic MTs in vitro. [12][13][14][15][16] Structurally, it is composed of an N-terminal globular domain that functions in subcellular targeting, 9,11,17,18 a class-specific neck and catalytic core that are essential for efficient MT depolymerization activity, 13,14,[19][20][21] and a C-terminal tail that is responsible for dimerization and the regulation of ATPase and depolymerization activity. 13,14,19,22 While the native protein is dimeric, a monomeric truncation consisting of the neck and catalytic core is sufficient for MT depolymerization in vitro and in cells.…”

PLK1 Phosphorylates Mitotic Centromere-associated Kinesin and Promotes Its Depolymerase Activity

“…MCAK/kif2c, the best characterized member of the Kin I subfamily, localizes dynamically at various mitotic structures, such as inner centromeres, outer kinetochores, centrosomes, spindle MTs, MT tips, and the spindle midzone (8, 14 -17). MCAK promotes catastrophe of both stable and dynamic MTs via depolymerizing MTs at both ends in vitro (3,18,19). Loss of MCAK function leads to extremely long spindle MTs, although overexpression of MCAK results in a short spindle in vivo (8,20).…”