Cloning of a complete protein-coding sequence of human platelet-type phosphofructokinase isozyme from pancreatic...

We have cloned a full length protein-coding sequence of human platelet-type phosphofructokinase (PFK) from pancreatic islet cDNA library. The platelet-type PFK was composed of 784 amino acids and had a deduced molecular weight of 85,590. Homologies in the primary structure with muscle- and liver-type PFK were 71 and 67%. Clear similarities of the amino and carboxyl halves with a prokaryotic PFK indicated an evolutionary event that duplicated genes of a prototype PFK fused into larger genes of eukaryotic PFKs. Amino acid residues constituting the binding sites for various allosteric modulators were well conserved, while a couple of different residues at the inhibitory ATP sites among three isozymes may partly explain their varied degree of sensitivities to ATP. Considerable amount of platelet-type PFK expression was demonstrated in brain, heart, kidney, colon and testis.