https://wiki.tiffa.net/w/index.php?action=history&feed=atom&title=Translations%3AVitamin_B12%2F66%2FenTranslations:Vitamin B12/66/en - Revision history2026-08-15T12:51:34ZRevision history for this page on the wikiMediaWiki 1.43.0https://wiki.tiffa.net/w/index.php?title=Translations:Vitamin_B12/66/en&diff=135260&oldid=prevFuzzyBot: Importing a new version from external source2024-04-05T11:15:36Z<p>Importing a new version from external source</p>
<p><b>New page</b></p><div>[[Methionine synthase]], coded by ''MTR'' gene, is a methyltransferase enzyme which uses the MeB<sub>12</sub> and reaction type 2 to transfer a methyl group from [[5-methyltetrahydrofolate]] to [[homocysteine]], thereby generating [[tetrahydrofolate]] (THF) and [[methionine]]. This functionality is lost in [[vitamin B12 deficiency|vitamin B<sub>12</sub> deficiency]], resulting in an increased [[homocysteine]] level and the trapping of [[folate]] as 5-methyl-tetrahydrofolate, from which THF (the active form of folate) cannot be recovered. THF plays an important role in DNA synthesis, so reduced availability of THF results in ineffective production of cells with rapid turnover, in particular red blood cells, and also intestinal wall cells which are responsible for absorption. THF may be regenerated via MTR or may be obtained from fresh folate in the diet. Thus all of the DNA synthetic effects of B<sub>12</sub> deficiency, including the [[megaloblastic anemia]] of [[pernicious anemia]], resolve if sufficient dietary folate is present. Thus the best-known "function" of B<sub>12</sub> (that which is involved with DNA synthesis, cell-division, and anemia) is actually a [[:wikt:facultative|facultative]] function which is mediated by B<sub>12</sub>-conservation of an active form of folate which is needed for efficient DNA production. Other cobalamin-requiring methyltransferase enzymes are also known in bacteria, such as Me-H<sub>4</sub>-MPT, coenzyme M methyltransferase.</div>FuzzyBot