HK3
Hexokinase 3 also known as HK3 is an enzyme which in humans is encoded by the HK2 gene on chromosome 5.Hexokinases phosphorylate glucose to produce glucose-6-phosphate (G6P), the first step in most glucose metabolism pathways. This gene encodes hexokinase 3. Similar to hexokinases 1 and 2, this allosteric enzyme is inhibited by its product glucose-6-phosphate. [provided by RefSeq, Apr 2009]
Structure
HK3 is one of four highly homologous hexokinase isoforms in mammalian cells. This protein has a molecular weight of 100 kDa and is composed of two highly similar 50-kDa domains at its N- and C-terminals. This high similarity, along with the and the existence of a 50-kDa hexokinase (HK4), suggests that the 100-kDa hexokinases originated from a 50-kDa precursor via gene duplication and tandem ligation. Like with HK1, only the C-terminal domain possesses catalytic ability, whereas the N-terminal domain is predicted to contain glucose and G6P binding sites, as well as a 32-residue region essential for proper protein folding. Moreover, the catalytic activity depends on the interaction between the two terminal domains. Unlike HK1 and HK2, HK3 lacks a mitochondrial binding sequence at its N-terminal.