Polo-Like Kinase 1-Mediated Phosphorylation of the GTP-Binding Protein Ran is Important for Bipolar Spindle Formation
Biochemical and Biophysical Research Communications
Polo-like kinase functions are essential for the establishment of a normal bipolar mitotic spindle, although precisely how Plk1 regulates the spindle is uncertain. In this study, we report that the small GTP/GDP-binding protein Ran is associated with Plk1. Plk1 is capable of phosphorylating co-immunoprecipitated Ran in vitro on serine-135 and Ran is phosphorylated in vivo at the same site during mitosis when Plk1 is normally activated. Cell cultures over-expressing a Ran S135D mutant have significantly higher numbers of abnormal mitotic cells than those over-expressing either wild-type or S135A Ran. The abnormalities in S135D mutant cells are similar to cells over-expressing Plk1. Our data suggests that Ran is a physiological substrate of Plk1 and that Plk1 regulates the spindle organization partially through its phosphorylation on Ran.
Binding sites, cell cycle proteins, cell line, tumor, guanosine triphosphate, mitosis, mutation, phosphorylation, protein binding, proto-oncogene proteins, serine
Feng, Yang; Yuan, Jin Hui; Maloid, Sharon C.; Fisher, Rebecca; Copeland, Terry D.; Longo, Dan L.; Conrads, Thomas P.; Veenstra, Timothy D.; Ferris, Andrea; Hughes, Steve; Dimitrov, Dimiter S.; and Ferris, Douglass K., "Polo-Like Kinase 1-Mediated Phosphorylation of the GTP-Binding Protein Ran is Important for Bipolar Spindle Formation" (2006). Pharmaceutical Sciences Faculty Publications. 389.