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J. Virol., 10 1996, 6902-6908, Vol 70, No. 10
A Porras, J Bennett, A Howe, K Tokos, N Bouck, B Henglein, S Sathyamangalam, B Thimmapaya and K Rundell
At least three regions of the simian virus 40 small-t antigen (small-t)
contribute to the protein's ability to enhance cellular transformation. As
we showed previously for rat F111 cells, one region includes sequences from
residues 97 to 103 that are involved in the binding and inhibition of
protein phosphatase 2A. In the present study, the role of the protein
phosphatase 2A binding region was confirmed in two additional
small-t-dependent transformation systems. Second, small-t was found to
provide a function previously identified as a large-T transformation
domain. Mutations in residues 19 to 28 of large-T affected its transforming
ability, but these mutations were complemented by a wild-type small-t. A
third region of small-t was also required for efficient transformation.
This region, the 42-47 region, is shared by large-T and small-t and
contains a conserved HPDKGG hexapeptide. The 42-47 region function could be
provided by either small-t or large-T in small-t-dependent systems.
Mutations in the 42-47 region reduced the ability of small-t to
transactivate the cyclin A promoter, of interest because small-t increased
endogenous cyclin A mRNA levels in both human and monkey cells, as well as
transactivating the promoter in transient assays.
Copyright © 1996, American Society for Microbiology
A novel simian virus 40 early-region domain mediates transactivation of the cyclin A promoter by small-t antigen and is required for transformation in small-t antigen-dependent assays
Department of Microbiology-Immunology, Northwestern University Medical Center, Chicago, Illinois 60611, USA.
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