The G2/M checkpoint phosphatase cdc25C is located within centrosomes.
cdc25C is a phosphatase which regulates the activity of the mitosis promoting factor cyclin B/cdk1 by dephosphorylation, thus triggering G(2)/M transition. The activity and the sub-cellular localisation of cdc25C are regulated by phosphorylation. It is well accepted that cdc25C has to enter the nucleus to activate the cyclin B/cdk1 complex at G(2)/M transition. Here, we will show that cdc25C is located in the cytoplasm at defined dense structures, which according to immunofluorescence analysis, electron microscopy as well as biochemical subfractionation, are proven to be the centrosomes. Since cyclin B and cdk1 are also located at the centrosomes, this subfraction of cdc25C might participate in the control of the onset of mitosis suggesting a further role for cdc25C at the centrosomes.
Busch
Corinna
C
Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, Gebäude 44, 66424 Homburg, Germany.
Barton
Olivia
O
Morgenstern
Eberhard
E
Götz
Claudia
C
Günther
Jürgen
J
Noll
Andreas
A
Montenarh
Mathias
M
D000818:Animals; D019556:COS Cells; D018797:Cell Cycle Proteins / Q000378:metabolism* / Q000648:ultrastructure; D045744:Cell Line, Tumor; D002502:Centrioles / Q000648:ultrastructure; D018385:Centrosome / Q000201:enzymology* / Q000648:ultrastructure; D002522:Chlorocebus aethiops; D016195:G2 Phase; D006801:Humans; D008938:Mitosis; D021381:Protein Transport; D013347:Subcellular Fractions / Q000201:enzymology; D020687:cdc25 Phosphatases / Q000378:metabolism* / Q000648:ultrastructure
D018797:Cell Cycle Proteins; C517009:CDC25C protein, human; D020687:cdc25 Phosphatases