title: A 53-kilodalton protein common to chemically and virally transformed cells shows extensive sequence similarities between species.
abstract: A heat-stable DNA-binding protein with subunits of about 53 kilodaltons (kDal) was purified from two virally transformed human cell lines (Epstein-Barr virus-positive Raji and Namalwa) and two mouse tumor cell lines (methylcholanthrene-induced Meth A sarcoma and TA3 mammary carcinoma). All four 53kDal proteins showed closely related total amino acid compositions, similar peptide maps, and identical NH2-terminal amino acid sequences for 20 residues. These 53-kDal proteins are therefore evolutionarily highly conserved, independent of whether they originate from virally or chemically transformed cells. The NH2-terminal sequence and the protein chain as a whole are not hydrophobic; however, some unexpected residue distributions were observed. Comparisons with other proteins reveal no clear sequence similarity with known tumor antigen structures, homologous immunoglobulins, or some other proteins of known sequence. Epstein-Barr virus-determined nuclear antigen also appears to have a different NH2-terminal sequence. Thus, the results show that the 53-kDal proteins represent a unique protein type with little species variation; this finding suggests that these proteins must perform an important common function in different transformation systems.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D002472:Cell Transformation, Viral; D006801:Humans; D051379:Mice; D008970:Molecular Weight; D009363:Neoplasm Proteins / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis
chemical_list: D000596:Amino Acids; D009363:Neoplasm Proteins; D010446:Peptide Fragments