The molecular mechanisms by which plant cells sense sugar levels are not understood, but current models (adapted from models for sugar sensing in yeast) favour hexokinase as the primary sugar sensor. However, the hypothesis that yeast hexokinase has a signalling function has not been supported by more recent studies and the idea that hexokinase is involved in sugar sensing in plants has yet to ...

The kinetic mechanism of rat skeletal muscle hexokinase (hexokinase II) was investigated in light of a proposal by Cornish-Bowden and his co-workers (Gregoriou, M., Trayer, I. P., and Cornish-Bowden, A. (1983) Eur. J. Biochem. 134, 283-288). These investigators reported that the kinetic mechanism is ordered, with glucose adding before ATP and ADP dissociating from hexokinase before glucose-6-P....

The initial step in Glc and Fru metabolism in plants is the hexokinase reaction, which catalyzes their irreversible phosphorylation. Recently, the hexokinase reaction has been hypothesized to be involved in the sensing and signal transmission of sugar levels in sugar repression of photosynthetic genes in plants (Jang and Sheen, 1994). Hexose-phosphorylating enzymes are classified according to t...

Hexokinase is the first enzyme in the glycolytic pathway that catalyzes the transfer of a phosphoryl group from ATP to glucose to form glucose-6-phosphate and ADP. Two yeast hexokinase isozymes are known, namely PI and PII. Here we redetermined the crystal structure of yeast hexokinase PI from Saccharomyces cerevisiae as a complex with its substrate, glucose, and refined it at 2.95 A resolution...

It was reported (1) that the hexokinase reaction, glucose + adenosine triphosphate + glucose-&phosphate + adenosine diphosphate, in extracts of muscle from diabetic rats could be inhibited by adrenal cortical extract, while the hexokinase activity in extracts of normal muscle was inhibited by a combination of anterior pituitary and adrenal cortical extracts. The inhibition was in both cases rel...

The phosphorylation of glucose by human erythrocyte hexokinase follows classical Michaelis-Menten kinetics; hexokinase manifests maximum activity at 5 mM glucose, and no further increase in activity can be measured at higher glucose concentrations. However, the erythrocytes of diabetics and normal erythrocytes incubated with high concentrations of glucose contain increased concentrations of glu...

Genes complementing the glucose-negative fructose-negative Saccharomyces cerevisiae triple mutant strain (hxkl hxk2 glk1), which lacks hexokinase PI, hexokinase PII, and glucokinase, were obtained from a pool of yeast DNA in the multicopy plasmid YEp13.