Analysis of two divergent rat genomic clones homologous to the transforming gene of Harvey murine sarcoma virus.

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Abstract
Harvey murine sarcoma virus (Ha-MuSV) is a mouse-rat recombinant retrovirus that encodes a protein designated p21, required for virally induced transformation. Using a radiolabeled DNA fragment from the p21 coding region, homologous DNA sequences were detected in the normal DNA of rats and several other vertebrate species. Many tested cells from these species contain low levels of a p21 protein that is highly related to viral 21. Two independent fragments from normal rat DNA containing sequences (sarc) homologous to the Ha-MuSV transforming region were cloned in the bacteriophage .lambda. vector Charon 4A Sarc sequences in the one fragment are completely colinear with the viral sequences and share apparently all restriction endonuclease sites. Sarc sequences in the 2nd fragment have several sets of intervening sequences and lack some restriction endonuclease sites found in the viral transforming region. Despite the presence of these intervening sequences in the 2nd sarc fragment, this sarc fragment was ligated to the long terminal repeat sequence of Ha-MuSV and cellular transformation and high levels of p21 expression were induced on transfection of this DNA to NIH 3T3 mouse cells. Elevated levels of p21, normally expressed at low levels in a variety of cells, apparently can induce cellular transformation.