ABSTRACT
A bacterial strain overproducing human prothymosin alpha was constructed based on the efficient T7 RNA polymerase transcription of human prothymosin alpha cDNA. The highest yield of the human prothymosin alpha, up to 30% of the total bacterial protein, was achieved with constructions containing 6-10 nucleotides between the Shine-Dalgarno sequence and initiation ATG codon. Unexpectedly, cells grown in the presence of inducer of T7 RNA polymerase synthesis produced substantially lower levels of prothymosin alpha than those grown in the absence of inducer. A simple procedure for prothymosin alpha isolation was elaborated, resulting in large amounts of electrophoretically pure and immunoactive protein.
Subject(s)
Escherichia coli/genetics , Protein Precursors/genetics , Thymosin/analogs & derivatives , Animals , Base Sequence , Cell Adhesion , Cell Division , Cloning, Molecular , DNA, Complementary , Electrophoresis, Polyacrylamide Gel , Humans , Mice , Molecular Sequence Data , Plasmids , Protein Precursors/isolation & purification , Protein Precursors/metabolism , Thymosin/genetics , Thymosin/isolation & purification , Thymosin/metabolismABSTRACT
A low-molecular-mass RNA from the cytoplasm of mouse Krebs II cells was found to be covalently linked to a protein with an apparent molecular mass of 13 kDa. The protein appears to be attached to the 5'-terminus of the RNA molecule, which is approx. 20 nucleotides long.
