Hexokinase

"A hexokinase is an enzyme that phosphorylates a six-carbon sugar, a hexose, to a hexose phosphate. In most tissues and organisms, glucose is the most important substrate of hexokinases, and glucose-6-phosphate the most important product."

"Genes that encode hexokinase have been discovered in each domain of life, ranging from bacteria, yeast, and plants to humans and other vertebrates. They are categorized as actin fold proteins, sharing a common ATP binding site core surrounded by more variable sequences that determine substrate affinities and other properties. Several hexokinase isoforms or isozymes providing different functions can occur in a single species. Hexokinase should not be confused with the liver's glucokinase. While hexokinase is capable of phosphorylating several hexoses, glucokinase acts with a 50-fold lower substrate affinity, and its only substrate is glucose."