Molecular cloning and sequencing of the glycogen phosphorylase gene from Escherichia coli

The glgP gene, which codes for glycogen phosphorylase, was cloned from a genomic library of Escherichia coli. The nucleotide sequence of the glgP gene contained a single open reading frame encoding a protein consisting of 790 amino acid residues. The glgP gene product, a polypeptide of Mr 87,000, was confirmed by SDS-polyacrylamide gel electrophoresis. The deduced amino acid sequence showed that homology between glgP of E. coli and rabbit glgP, human glgP, potato glgP, and E. coli malP was 48.6, 48.6, 42.3, and 46.1%, respectively. Within this homologous region, the active site, glycogen storage site, and pyridoxal-5'-phosphate binding site are well conserved. The enzyme activity of glycogen phosphorylase increased after introduction on a multicopy of the glgP gene.