# PRODUCTS OF THE TRANSFORMING GENES OF POLYOMA VIRUS

> **NIH NIH R01** · TUFTS UNIVERSITY BOSTON · 1990 · $176,688

## Abstract

This proposal concerns the gene products of polyoma virus required for
virus growth and transformation.  We are particularly concerned with how
post-synthetic modifications regulate protein function.  We therefore
concentrate on large T and middle T, which are both phosphoproteins.  Our
goal is to learn how these proteins function and how phosphorylation
contributes to that function.  Our approach is both biochemical and genetic.

Middle T associates with pp60c-src, the cell homologue of the transforming
protein of Rous sarcoma virus.  It is likely that the action of middle T in
transformation results from this interaction.  We will test this directly
by creating mutants of pp60c-src designed to block middle T mediated
transformation.  We will probe the interaction between these two proteins
with hybrid molecules containing pp60c-src and pp60v-src sequences and with
pp60v-src mutants. Biochemical evidence suggests middle T serine
phosphorylation is required for association with pp60c-src.  This will be
tested directly.  The serine phosphorylation sites will be identified.
Oligonucleotide mutagenesis will then be used to create mutants lacking the
phosphorylation sites.  The biology and biochemistry of these mutants will
be compared to wild type.  The middle T/pp-60c-src complex possesses
tyrosine kinase activity; tyrosine phosphorylation of cell proteins has
been demonstrated in RSV-transformed cells.  However, the complexes also
possess phosphatidylinositol kinase activity.  Experiments involving
calcium release and protein kinase C activation will be carried out to
decide whether in vivo alterations in phosphatidylinositol metabolism are
important for transformation.

Large T antigen, which is important for DNA replication and RNA
transcription, is a valuable model for non-histone chromosomal proteins.
Using ts-a and hr-t mutants, we have obtained evidence that some of the
phosphorylations may be required for function.  Mapping of the sites and
mutagenesis will be used to test this hypothesis.  Phosphorylation patterns
will be examined in different cells and different subcellular locations to
to try to assess the importance of the other phosphorylations of large T.
In these analyses, we will use both wild type virus and the large number of
large T mutants now available.

## Key facts

- **NIH application ID:** 3172492
- **Project number:** 5R01CA034722-08
- **Recipient organization:** TUFTS UNIVERSITY BOSTON
- **SAM.gov UEI:** C1F5LNUF7W86
- **Principal Investigator:** BRIAN S SCHAFFHAUSEN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1990
- **Award amount:** $176,688
- **Award type:** 5
- **Project period:** 1983-04-01 → 1991-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3172492

## Citation

> US National Institutes of Health, RePORTER application 3172492, PRODUCTS OF THE TRANSFORMING GENES OF POLYOMA VIRUS (5R01CA034722-08). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3172492. Licensed CC0.

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