Nuclear export signal in CDC25B.
CDC25B is a dual-specificity phosphatase that activates CDK1/cyclin B. The nuclear exclusion of CDC25B is controlled by the binding of 14-3-3 to the nuclear export signal (NES) of CDC25B, which was reported to be amino acids H28 to L40 in the N-terminal region of CDC25B. In studying the subcellular localization of CDC25B, we found a functional NES at V52 to L65, the sequence of which is VTTLTQTMHDLAGL, where bold letters are leucine or hydrophobic amino acids frequently seen in an NES. The deletion of this NES sequence caused the mutant protein to locate exclusively in nuclei, while NES-fused GFP was detected in the cytoplasm. Moreover, the introduction of point mutations at some of the critical amino acids impaired cytoplasmic localization. Treatment with leptomycin B, a potent inhibitor of CRM1/exportin1, disrupted the cytoplasmic localization of both Flag-tagged CDC25B and NES-fused GFP. From these results, we concluded that the sequence we found is a bona fide NES of CDC25B.
Division of Life Science, Graduate School of Natural Science and Technology, Kanazawa University, General Education Hall, Kakuma-machi, Kanazawa 920-1192, Japan.
Sanae
S
Uchida
Motoaki
M
Ohtsubo
Mari
M
Shimura
Masato
M
Hirata
Hitoshi
H
Nakagama
Tsukasa
T
Matsunaga
Minoru
M
Yoshida
Yukihito
Y
Ishizaka
Katsumi
K
Yamashita
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000032:analysis / Q000737:chemistry* / Q000235:genetics; D002467:Cell Nucleus / Q000737:chemistry* / Q000378:metabolism; D003593:Cytoplasm / Q000737:chemistry; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008969:Molecular Sequence Data; D009154:Mutation; D021382:Protein Sorting Signals; D020687:cdc25 Phosphatases / Q000032:analysis / Q000737:chemistry* / Q000235:genetics
D018797:Cell Cycle Proteins; D005231:Fatty Acids, Unsaturated; D021382:Protein Sorting Signals; C517008:CDC25B protein, human; D020687:cdc25 Phosphatases; C038753:leptomycin B