Pyruvate kinase:

Pyruvate kinase catalyzes the third irreversible step in glycolysis.  It is activated through fructose 1, 6-bisphosphate.  The ATP and amino acid alanine allosterically inhibit the enzyme so which glycolysis slows when supplies of biosynthetic precursors and ATP (indicated through the levels of Ala) are already sufficiently high. Additionally, in a control same to that for PFK, when the blood glucose concentration is low, glucagon is stimulates and released phosphorylation of the enzyme through a cAMP cascade. This covalent modification inhibits the enzyme so in which glycolysis slows down in times of low blood glucose levels.