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GalT encodes for the protein galactosyltransferase which catalyzes the transfer of a galactose sugar to an acceptor, forming a glycosidic bond. [5] GalK encodes for a kinase that phosphorylates α-D-galactose to galactose 1-phosphate. [6] Lastly, galM catalyzes the conversion of β-D-galactose to α-D-galactose as the first step in galactose ...
The Gal4 transcription factor is a positive regulator of gene expression of galactose-induced genes. [1] This protein represents a large fungal family of transcription factors, Gal4 family, which includes over 50 members in the yeast Saccharomyces cerevisiae e.g. Oaf1, Pip2, Pdr1, Pdr3, Leu3. [2]
Galactose (/ ɡ ə ˈ l æ k t oʊ s /, galacto-+ -ose, "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweet as glucose, and about 65% as sweet as sucrose. [2] It is an aldohexose and a C-4 epimer of glucose. [3] A galactose molecule linked with a glucose molecule forms a lactose molecule.
After separation from glucose, galactose travels to the liver for conversion to glucose. [12] Galactokinase uses one molecule of ATP to phosphorylate galactose. [2] The phosphorylated galactose is then converted to glucose-1-phosphate, and then eventually glucose-6-phosphate, which can be broken down in glycolysis. [2]
O-galactose is commonly found on lysine residues in collagen, which often have a hydroxyl group added to form hydroxylysine. Because of this addition of an oxygen, hydroxylysine can then be modified by O-glycosylation.
X-ray crystallography experiments have shown that one Mg 2+ ion is coordinated by a phosphoryl oxygen on glucose 1-phosphate and by an α-phosphoryl oxygen on UTP. [5] In addition to stabilizing the negatively charged phosphates, Mg 2+ is thought to orient the glucose 1-phosphate for nucleophilic attack of the α-phosphorus of UTP. [20]
Galactosemia, a rare metabolic disorder characterized by decreased ability to metabolize galactose, can be caused by a mutation in any of the three enzymes in the Leloir pathway. [2] Galactokinase deficiency , also known as galactosemia type II, is a recessive metabolic disorder caused by a mutation in human galactokinase.
α-Galactosidase ( EC 3.2.1.22, α-GAL, α-GAL A; systematic name α-D-galactoside galactohydrolase) is a glycoside hydrolase enzyme that catalyses the following reaction: [1] Hydrolysis of terminal, non-reducing α- D -galactose residues in α- D -galactosides, including galactose oligosaccharides, galactomannans and galactolipids