Molecular cloning and primary structure analysis of the mouse mammary tumor virus-related element from dwarf hamster genome

Eleven recombinant bacteriophages carrying mouse mammary tumor virus (MMTV)-related sequences (MRS) were isolated from the genomic library of the dwarf hamster (Phodopus sungorus) using radioactively labeled DNA of MMTV as a hybridization probe. There are approximately 50 copies of MRS-Ps per genome, as estimated by the number of positive signals on the autoradiogram of the primary screening plate. MRS of Phodopus sungorus (MRS-Ps) contain regions homologous to the LTR, pol, and, probably, env, but not gag genes of MMTV. A 0.9 kb MRS-Ps fragment was sequenced and proved to be 63% identical to the MMTV pol gene sequence. However, all absolute frames contain multiple stop codons and do not seem to be expressed.