title: High-level synthesis in Escherichia coli of the SV40 small-t antigen under control of the bacteriophage lambda pL promoter.
abstract: Several plasmids were constructed in which the SV40 small-t antigen gene was inserted in close proximity downstream from the thermoinducible leftward promoter (pL) of bacteriophage lambda. Upon temperature induction the best of our constructions expressed a small-t-related 19 000-dalton polypeptide in an amount corresponding to approx. 2.5% of total de novo protein synthesis. This 19 000-dalton protein was identified as small-t by specific immunoprecipitation with anti-T serum and by two-dimensional fingerprint analysis. In addition to the 19 000-dalton product, representative plasmids expressed fairly large amounts (up to 7% of total de novo protein synthesis) of a protein with an apparent Mr of 14 500. This 14 500-dalton polypeptide was shown to be related to authentic small-t. Presumably the secondary structure of the mRNA starting at pL is such that translation initiation at an internal AUG codon of the small-t gene is favored over initiation at the true initiating codon.
mesh_terms: D000918:Antibody Specificity; D000937:Antigen-Antibody Reactions; D000956:Antigens, Viral / Q000032:analysis / Q000235:genetics*; D010582:Bacteriophage lambda / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D008970:Molecular Weight; D009876:Operon; D010957:Plasmids; D014176:Protein Biosynthesis; D013539:Simian virus 40 / Q000276:immunology*
chemical_list: D000956:Antigens, Viral