Galactokinase: An enzyme that catalyzes reversibly the formation of galactose 1-phosphate and ADP from ATP and D-galactose. Galactosamine can also act as the acceptor. A deficiency of this enzyme results in GALACTOSEMIA. EC 22.214.171.124.Galactose: An aldohexose that occurs naturally in the D-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase (GALACTOSE-1-PHOSPHATE URIDYL-TRANSFERASE DEFICIENCY DISEASE) causes an error in galactose metabolism called GALACTOSEMIA, resulting in elevations of galactose in the blood.UTP-Hexose-1-Phosphate Uridylyltransferase: An enzyme that catalyzes the synthesis of UDPgalactose from UTP and galactose-1-phosphate. It is present in low levels in fetal and infant liver, but increases with age, thereby enabling galactosemic infants who survive to develop the capacity to metabolize galactose. EC 126.96.36.199.Galactosemias: A group of inherited enzyme deficiencies which feature elevations of GALACTOSE in the blood. This condition may be associated with deficiencies of GALACTOKINASE; UDPGLUCOSE-HEXOSE-1-PHOSPHATE URIDYLYLTRANSFERASE; or UDPGLUCOSE 4-EPIMERASE. The classic form is caused by UDPglucose-Hexose-1-Phosphate Uridylyltransferase deficiency, and presents in infancy with FAILURE TO THRIVE; VOMITING; and INTRACRANIAL HYPERTENSION. Affected individuals also may develop MENTAL RETARDATION; JAUNDICE; hepatosplenomegaly; ovarian failure (PRIMARY OVARIAN INSUFFICIENCY); and cataracts. (From Menkes, Textbook of Child Neurology, 5th ed, pp61-3)Galactosephosphates: Phosphoric acid esters of galactose.UDPglucose 4-Epimerase: A necessary enzyme in the metabolism of galactose. It reversibly catalyzes the conversion of UDPglucose to UDPgalactose. NAD+ is an essential component for enzymatic activity. EC 188.8.131.52.Phosphotransferases: A rather large group of enzymes comprising not only those transferring phosphate but also diphosphate, nucleotidyl residues, and others. These have also been subdivided according to the acceptor group. (From Enzyme Nomenclature, 1992) EC 2.7.Hypocrea: A genus of fungus in the family Hypocreaceae, order HYPOCREALES. Anamorphs include TRICHODERMA.Galactose Dehydrogenases: D-Galactose:NAD(P)+ 1-oxidoreductases. Catalyzes the oxidation of D-galactose in the presence of NAD+ or NADP+ to D-galactono-gamma-lactone and NADH or NADPH. Includes EC 184.108.40.206 and EC 220.127.116.11.UDPglucose-Hexose-1-Phosphate Uridylyltransferase: An enzyme that catalyzes the transfer of UMP from UDPglucose to galactose 1-phosphate, forming UDPgalactose and glucose 1-phosphate. Deficiency in this enzyme is the major cause of GALACTOSEMIA. EC 18.104.22.168.FucoseTetrahymena: A genus of ciliate protozoa commonly used in genetic, cytological, and other research.Adrenergic Agonists: Drugs that bind to and activate adrenergic receptors.Genes: A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.Lactose: A disaccharide of GLUCOSE and GALACTOSE in human and cow milk. It is used in pharmacy for tablets, in medicine as a nutrient, and in industry.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Kluyveromyces: An ascomycetous yeast of the fungal family Saccharomycetaceae, order SACCHAROMYCETALES.Enzyme Repression: The interference in synthesis of an enzyme due to the elevated level of an effector substance, usually a metabolite, whose presence would cause depression of the gene responsible for enzyme synthesis.Selenomethionine: Diagnostic aid in pancreas function determination.Operon: In bacteria, a group of metabolically related genes, with a common promoter, whose transcription into a single polycistronic MESSENGER RNA is under the control of an OPERATOR REGION.Saccharomyces: A genus of ascomycetous fungi of the family Saccharomycetaceae, order SACCHAROMYCETALES.Uracil NucleotidesNucleotidyltransferases: A class of enzymes that transfers nucleotidyl residues. EC 2.7.7.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.