Protein interactions play an important role in transformation by DNA tumor viruses. They might result either in activation of proto-oncogenes or, as recently suggested, in inactivation of anti-oncogenes. Polyoma medium T antigen, the principal transforming protein of polyoma, binds to the pro-oncogenes pp60c-src and pp62c-yes, thereby increasing their protein-tyrosine kinase activity. Medium T also binds to two cellular proteins of 61,000 and 37,000 daltons (61K and 37K proteins), and genetic evidence indicates that these proteins are involved in transformation. It is possible that they represent anti-oncogenes. A large fraction of the cDNA encoding the 61K protein has been sequenced, and it appears that it belongs to a new family of proteins. The goals of this proposal are (1) to purify the 37K protein and to clone and sequence its corresponding cDNA, in addition to finishing sequencing of the 61K protein cDNA; (2) to produce large quantities of the 61K and 37K proteins; (3) to prepare polyclonal and monoclonal antibodies against the 61K and 37K proteins; (4) to study their expression in the cell cycle, in different organs and during development; (5) to study the in vitro complex formation between the 61K/337K proteins and mT antigen; (6) to microinject antibodies against the 61K/37K proteins to test the effect of blocking complex formation in vivo on the biology of the cell.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
2R01CA036111-06A1
Application #
3173609
Study Section
Virology Study Section (VR)
Project Start
1983-12-01
Project End
1994-11-30
Budget Start
1989-12-01
Budget End
1990-11-30
Support Year
6
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of California San Diego
Department
Type
Schools of Medicine
DUNS #
077758407
City
La Jolla
State
CA
Country
United States
Zip Code
92093
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Walter, Gernot; Zhou, Jin; Ruediger, Ralf (2007) Purification of PP2A holoenzymes by sequential immunoprecipitation with anti-peptide antibodies. Methods Mol Biol 365:113-26
Petersen, Paris; Chou, Danny M; You, Zhongsheng et al. (2006) Protein phosphatase 2A antagonizes ATM and ATR in a Cdk2- and Cdc7-independent DNA damage checkpoint. Mol Cell Biol 26:1997-2011
Zhou, Jin; Pham, Huong T; Walter, Gernot (2003) The formation and activity of PP2A holoenzymes do not depend on the isoform of the catalytic subunit. J Biol Chem 278:8617-22
Zhou, Jin; Pham, Huong T; Ruediger, Ralf et al. (2003) Characterization of the Aalpha and Abeta subunit isoforms of protein phosphatase 2A: differences in expression, subunit interaction, and evolution. Biochem J 369:387-98
Chou, Danny M; Petersen, Paris; Walter, Johannes C et al. (2002) Protein phosphatase 2A regulates binding of Cdc45 to the prereplication complex. J Biol Chem 277:40520-7
Ruediger, R; Pham, H T; Walter, G (2001) Disruption of protein phosphatase 2A subunit interaction in human cancers with mutations in the A alpha subunit gene. Oncogene 20:10-5
Colella, S; Ohgaki, H; Ruediger, R et al. (2001) Reduced expression of the Aalpha subunit of protein phosphatase 2A in human gliomas in the absence of mutations in the Aalpha and Abeta subunit genes. Int J Cancer 93:798-804
Ruediger, R; Pham, H T; Walter, G (2001) Alterations in protein phosphatase 2A subunit interaction in human carcinomas of the lung and colon with mutations in the A beta subunit gene. Oncogene 20:1892-9
Brewis, N; Ohst, K; Fields, K et al. (2000) Dilated cardiomyopathy in transgenic mice expressing a mutant A subunit of protein phosphatase 2A. Am J Physiol Heart Circ Physiol 279:H1307-18

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