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The lactase promoter is 150 base pairs long and is located just upstream of the site of transcription initiation.
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lactase and promoter
There is no lactose to inhibit the repressor, so the repressor binds to the operator, which obstructs the RNA polymerase from binding to the promoter and making lactase.
Lactose is inhibiting the repressor, allowing the RNA polymerase to bind with the promoter, and express the genes, which synthesize lactase.
There is no lactose to inhibit the repressor, so the repressor binds to the operator, which obstructs the RNA polymerase from binding to the promoter and making lactase.
Lactose is inhibiting the repressor, allowing the RNA polymerase to bind with the promoter, and express the genes, which synthesize lactase.
There is no lactose to inhibit the repressor, so the repressor binds to the operator, which obstructs the RNA polymerase from binding to the promoter and making lactase.
Lactose is inhibiting the repressor, allowing the RNA polymerase to bind with the promoter, and express the genes, which synthesize lactase.
There is no lactose to inhibit the repressor, so the repressor binds to the operator, which obstructs the RNA polymerase from binding to the promoter and making lactase.
Lactose is inhibiting the repressor, allowing the RNA polymerase to bind with the promoter, and express the genes, which synthesize lactase.
There is no lactose to inhibit the repressor, so the repressor binds to the operator, which obstructs the RNA polymerase from binding to the promoter and making lactase.
Lactose is inhibiting the repressor, allowing the RNA polymerase to bind with the promoter, and express the genes, which synthesize lactase.
There is no lactose to inhibit the repressor, so the repressor binds to the operator, which obstructs the RNA polymerase from binding to the promoter and making lactase.
Lactose is inhibiting the repressor, allowing the RNA polymerase to bind with the promoter, and express the genes, which synthesize lactase.
It was also proven that the position-13910 has an enhancer function on the lactase promoter ( the promoter facilitates the transcription of the LCT gene ).
lactase and is
Typically, to generate the name of an enzyme, the suffix-ase is added to the name of its substrate ( e. g., lactase is the enzyme that cleaves lactose ) or the type of reaction ( e. g., DNA polymerase forms DNA polymers ).
In humans, lactase is encoded by the LCT gene.
The optimum temperature for lactase is about 77 ° F ( 25 ° C ) for its activity and has an optimum pH of 6.
While it is most notably a member of the β-galactosidase enzymatic class, lactase also has glucosidase and glycosylceramidase activity.
The overall reaction that lactase catalyzes is C < sub > 12 </ sub > H < sub > 22 </ sub > O < sub > 11 </ sub > + H < sub > 2 </ sub > O → C < sub > 6 </ sub > H < sub > 12 </ sub > O < sub > 6 </ sub > + C < sub > 6 </ sub > H < sub > 12 </ sub > O < sub > 6 </ sub > + heat.
Studies of E. coli lactase have proposed that hydrolysis is initiated when a glutamate nucleophile on the enzyme attacks from the axial side of the galactosyl carbon in the β-glycosidic bond.
It can be divided into five domains: ( i ) a 19 amino acid cleaved signal sequence ; ( ii ) a large prosequence domain that is not present in mature lactase ; ( iii ) the mature lactase segment ; ( iv ) a membrane spanning hydrophobic anchor ; and ( v ) a short hydrophilic carboxyl terminus.
In the human enzyme, the lactase activity has been connected to Glu-1749 while Glu-1273 is the site of phlorizin hydrolase function.
In most of the world ’ s population, lactase transcription is down-regulated after weaning, resulting in diminished lactase expression in the small intestine.
Some population segments exhibit lactase persistence resulting from a mutation that is postulated to have occurred 5000-10, 000 years ago, coinciding with the rise of cattle domestication.
Studies of hypolactasia onset have demonstrated that despite polymorphisms there is little difference in lactase expression in infants, showing that the mutations become increasingly relevant during development.
The enzyme needed to digest lactose, lactase, reaches its highest levels in the small intestines after birth and then begins a slow decline unless milk is consumed regularly.
Eventually, the lactase will digest all of the lactose, until there is none to bind to the repressor.
For those who with lactose intolerance, taking digestive enzymes containing lactase when consuming dairy products is recommended.
And milk treated with lactase is also safe for the lactose intolerant.
Lactose intolerance, also called lactase deficiency and hypolactasia, is the inability to digest lactose, a sugar found in milk and to a lesser extent milk-derived dairy products.
It is estimated that 75 % of adults worldwide show some decrease in lactase activity during adulthood.
This distribution is now thought to have been caused by recent natural selection favoring lactase persistant individuals in cultures that rely on dairy products.
lactase and base
Joel Hirschhorn of Harvard Medical School discovered that lactase persistence was due to the presence of a haplotype composed of more than 1 million nucleotide base pairs, including the lactase gene.
lactase and long
The LCT gene which encodes the lactase protein is located on the long arm ( q ) of chromosome 2 in region 21.
lactase and located
Since both SNPs are located in the same gene, this has led to a genetic means of testing lactase expression in individuals.
MCM6 contains two of the regulatory regions for LCT, the gene encoding the protein lactase, located in two of the MCM6 introns, approximately 14 kb (- 13910 ) and 22 kb (- 22018 ) upstream of LCT.
lactase and upstream
Studies have linked the occurrence of lactase persistence to two different single-nucleotide polymorphisms about 14 and 22 kilobases upstream of the 5 ’- end of the LPH gene.
It was found that C − 13910 ( C at position-13910 upstream of the gene LCT ) and G − 22018 ( G at position-22018 ) are related to lactase non-persistence while the T − 13910 and A − 22018 are related to lactase persistence.
lactase and .
As most humans age, the production of lactase, the enzyme that hydrolyzes lactose back into glucose and galactose, typically decreases.
This results in lactase deficiency, also called lactose intolerance.
In addition, human beings, like other mammals, after they are weaned, stop producing lactase enzymes ( needed to digest milk ) unless they drink milk.
Deficiency of lactase in humans causes lactose intolerance.
Schematic of processing and localization of human lactase translational product.
Mature human lactase consists of a single 160 kDa polypeptide chain that localizes to the brush border membrane of intestinal epithelial cells.
Humans are born with high levels of lactase expression.
Diminished lactase expression causes the common symptoms of adult-type hypolactasia, or lactose intolerance.
Both mutations, C → T at position-13910 and T → A at position-22018, have been independently linked to lactase persistence.
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