Aldose reductase (EC 1.1.1.21 ) is a member of the monomeric, NADPH-dependent aldoketoreductase family. It catalyzes the reduction of a number of aldehydes, including the aldehyde form of glucose, which is reduced to the corresponding sugar alcohol, sorbitol. Sorbitol is subsequently metabolized to fructose by sorbitol dehydrogenase. Under normal conditions, this pathway plays a minor role in glucose metabolism in most tissues. In diabetic hyperglycemia, however, cells undergoing insulin-independent uptake of glucose produce significant quantities of sorbitol. The sorbitol accumulates in cells because of its poor penetration across cellular membranes and its slow metabolism by sorbitol dehydrogenase. The resulting hyperosmotic stress to cells may be a cause of diabetic complications such as neuropathy, retinopathy, and cataracts.
NCBI Summary:
This gene encodes a member of the aldo/keto reductase superfamily, which consists of more than 40 known enzymes and proteins. This member catalyzes the reduction of a number of aldehydes, including the aldehyde form of glucose, and is thereby implicated in the development of diabetic complications by catalyzing the reduction of glucose to sorbitol. There are a few putative pseudogenes for this gene, and one of them has been confirmed and mapped to chromosome 3.
General function
Enzyme, Oxidoreductase
Comment
Cellular localization
Cytoplasmic
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Ovarian function
Follicle development
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Expression regulated by
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Ovarian localization
Granulosa
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Kaneko T, et al reported colocalization of polyol-metabolizing enzymes and immunological detection of fructated proteins in the female reproductive system of the rat.
The expression of aldose reductase (AR) and sorbitol dehydrogenase (SDH), which, in concert, catalyze the conversion of glucose to fructose via sorbitol, in the rat ovary, oviduct, and uterus, was investigated by immunohistochemical and biochemical analyses. The activities and protein levels of AR and SDH were higher in the ovary than in the oviduct and uterus. A strong immunoreactivity to the anti-AR antibody was observed in granulosa cells and epithelia of the oviduct, endometrium, and endometrial glands, and virtually the same tissues were strongly stained with the anti-SDH antibody. The application of an anti-fructated lysine antibody, which detects an adduct of fructose with the epsilon-amino group of lysine in proteins, in this study detected marked staining mainly in the egg and luminal surface of the oviductal epithelia. Collectively, these data indicate that fructose is produced by coordinately expressed AR and SDH in the egg and epithelia of the oviduct and suggest that the resulting sorbitol and fructose can be used as energy sources for spermatozoa motility during the fertilization process. The abundance of AR compared with SDH suggests that it also plays an additional role in the reproductive system, which might include a source of reducing power and protection against toxic carbonyl compounds.