6-phosphofructo-2-kinase <p>6-Phosphofructo-2-kinase (<db_xref db="EC" dbkey="2.7.1.105"/>, <db_xref db="EC" dbkey="3.1.3.46"/>) is a bifunctional enzyme that catalyses both the synthesis and the degradation of fructose-2, 6-bisphosphate. The fructose-2,6-bisphosphatase reaction involves a phosphohistidine intermediate. The catalytic pathway is:<reaction>ATP + D-fructose 6-phosphate = ADP + D-fructose 2,6-bisphosphate</reaction><reaction>D-fructose 2,6-bisphosphate + H₂O = 6-fructose 6-phosphate + P_i</reaction>The enzyme is important in the regulation of hepatic carbohydrate metabolism and is found in greatest quantities in the liver, kidney and heart. In mammals, several genes often encode different isoforms, each of which differs in its tissue distribution and enzymatic activity [<cite idref="PUB00001475"/>]. The family described here bears a resemblance to the ATP-driven phospho-fructokinases, however, they share little sequence similarity, although a few residues seem key to their interaction with fructose 6-phosphate [<cite idref="PUB00000264"/>].</p><p>This domain forms the N-terminal region of this enzyme, while <db_xref db="INTERPRO" dbkey="IPR013078"/> forms the C-terminal domain.</p>