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Tobacco retinoblastoma-related protein phosphorylated by a distinct cyclin-dependent kinase complex with Cdc2/cyclin D in vitro
被引:128
作者:
Nakagami, H
[1
]
Sekine, M
[1
]
Murakami, H
[1
]
Shinmyo, A
[1
]
机构:
[1] Nara Inst Sci & Technol, Grad Sch Biol Sci, Nara 6300101, Japan
关键词:
D O I:
10.1046/j.1365-313X.1999.00449.x
中图分类号:
Q94 [植物学];
学科分类号:
071001 ;
摘要:
The retinoblastoma (Rb) protein was originally identified as a product of a tumour suppressor gene that plays a pivotal role in regulating both the cell cycle and differentiation in mammals. The growth-suppressive activity of Rb is regulated by phosphorylation with cyclin-dependent kinase (CDK), and inactivation of the Rb function is one of the critical steps for transition from the G1 to the S phase. We report here the cloning of a cDNA (NtRb1) from Nicotiana tabacum which encodes a Rb-related protein, and show that this gene is expressed in all the organs examined at the mRNA level. We have demonstrated that NtRb1 interacts with tobacco cyclin D by using yeast two-hybrid and in vitro binding assays. In mammals, cyclin D can assemble with CDK4 and CDK6, but not with Cdc2, to form active complexes. Surprisingly, tobacco cyclin D and Cdc2 proteins can form a complex in insect cells, which is able to phosphorylate tobacco Rb-related protein in vitro. Using immunoprecipitation with the anti-cyclin D antibody, cyclin D can be found in a complex with Cdc2 in suspension-cultured tobacco BY-2 cells. These results suggest that the cdc2 gene modulates the cell cycle through the phosphorylation of Rb-related protein by forming an active complex with cyclin D in plants.
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页码:243 / 252
页数:10
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