title: Properties of simian virus 40 small t antigen overproduced in bacteria.
abstract: We constructed a series of bacterial plasmids which contained the Escherichia coli lac promoter fused to a simian virus 40 restriction fragment coding for small t antigen. These plasmids expressed different levels of intact viral protein depending on the length of the constructed ribosome binding site. Small t antigen synthesized by the most efficient producer, HP1, constituted 0.5 to 1% of the total cellular protein. On the basis of extensive characterization by immunoprecipitation, gel electrophoresis, isoelectric focusing, tryptic fingerprint analysis, and chromatographic properties, this plasmid-encoded protein was virtually identical to authentic simian virus 40 small t antigen. Partial purification of the HP1-encoded and authentic small t antigens revealed the presence of both monomeric and multimeric forms.
mesh_terms: D000951:Antigens, Neoplasm / Q000096:biosynthesis* / Q000276:immunology / Q000302:isolation & purification; D000956:Antigens, Viral / Q000096:biosynthesis* / Q000276:immunology / Q000302:isolation & purification; D000957:Antigens, Viral, Tumor; D001483:Base Sequence; D002850:Chromatography, Gel; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D009876:Operon; D010957:Plasmids; D012270:Ribosomes / Q000378:metabolism; D013539:Simian virus 40 / Q000276:immunology*
chemical_list: D000951:Antigens, Neoplasm; D000956:Antigens, Viral; D000957:Antigens, Viral, Tumor