The Nuclear Transport Factor Kap121 Is Required for Stability of the Dam1 Complex and Mitotic Kinetochore Bi-orientation

Publication date: Available online 3 March 2016
Source:Cell Reports
Author(s): Lucas V. Cairo, Richard W. Wozniak
The karyopherin (Kap) family of nuclear transport factors facilitates macromolecular transport through nuclear pore complexes (NPCs). The binding of Kaps to their cargos can also regulate, both temporally and spatially, the interactions of the cargo protein with interacting partners. Here, we show that the essential yeast Kap, Kap121, binds Dam1 and Duo1, components of the microtubule (MT)-associated Dam1 complex required for linking dynamic MT ends with kinetochores (KTs). Like mutations in the Dam1 complex, loss of Kap121 function compromises the formation of normal KT-MT attachments during mitosis. We show that the stability of the Dam1 complex in vivo is dependent on its association with Kap121. Furthermore, we show that the Kap121/Duo1 complex is maintained in the presence of RanGTP but Kap121 is released by the cooperative actions of RanGTP and tubulin. We propose that Kap121 stabilizes the Dam1 complex and participates in escorting it to spindle MTs.

Graphical abstract

Teaser

Kap121 is a yeast nuclear transport factor capable of moving proteins through nuclear pore complexes. Cairo and Wozniak show that Kap121 also regulates kinetochore bi-orientation by binding to and stabilizing the Dam1 complex until the complex associates with spindle microtubules.


from #AlexandrosSfakianakis via Alexandros G.Sfakianakis on Inoreader http://ift.tt/1UDW059
via IFTTT