Identification of SV40 large T-antigen-associated proteins in cardiomyocytes from transgenic mice.

A cell line derived from transgenic mice expressing the SV40 large T-antigen oncogene in the heart was used to identify cardiomyocyte targets for T-antigen binding. A novel protein of molecular mass of 193 kDa was identified as an associated protein by virtue of its ability to be co-immunoprecipitated with multiple anti-T-antigen antibodies. Two previously described proteins, p120 and p53, were also observed to complex with T-antigen in transformed cardiomyocytes. In addition, several proteins that cross-reacted with either anti-T-antigen or anti-p53 antibodies were identified. Two of these proteins, of apparent molecular masses of 250 and 110 kDa, were only observed in cardiomyocytes. Expression of a third cross-reacting protein of a molecular mass of 180 kDa appeared to be dependent on the growth status of the cells. These proteins may be important constituents of the cardiomyocyte cell cycle, as well as potential cellular targets for myocardial regeneration.