Cloning and expression of a catalytic core bovine brain 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase

A cDNA encoding the catalytic core of a novel brain 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase isoenzyme was isolated from a λgt10 bovine brain library. This brain cDNA begins and ends in an open reading frame encoding a peptide of 476 amino acids. This peptide contains both the catalytic kinase and bisphosphatase domains and has an overall 65% and 67% identity with the bovine heart and liver isozymes, respectively, whereas the NH₂ and COOH-termini are divergent. An active catalytic core brain bifunctional enzyme was expressed in E. coli using a T7 RNA polymerase-based expression system. These results support the presence of a distinct gene coding for the protein in bovine brain.