Nucleotide sequence of the ampicillin resistance gene of Escherichia coli plasmid pBR322.

I have determined the nucleotide sequence of the ampicillin resistance gene of pBR322, an Escherichia coli plasmid that encodes a penicillin beta-lactamase. This gene codes for a protein of 286 amino acid residues. The first 23 amino acids presumably form a signal for secretion, because they do not appear in the mature enzyme, whose partial amino acid sequence has been determined independently.