Menaquinone-4 is a member of the menaquinone family with four isoprene-derived units in its side chain. Its formula is . The numeral in the name describes the side chain, rather than four molecules of Vitamin K or a fourfold concentration.[ref]
PubChem Compound database by National Center for Biotechnology Information. Menatetrenone, CID5282367, formula, structural description and menaquinone-4 synonym
In 2010, reducing UBIAD1 expression in human cells reduced formation of labelled menaquinone-4 from labelled vitamin-K derivatives. Expressing the candidate enzyme in insect cells supplied complementary evidence, and deuterium nuclear magnetic resonance identified the product.[ref]
Identification of UBIAD1 as a novel human menaquinone-4 biosynthetic enzyme by Kimie Nakagawa and others. Abstract, interference, heterologous expression and chemical identification
The experiments address different parts of the proposed mechanism. A loss-of-function comparison tests whether a component is required in the original system; expression in another system tests whether it can support the conversion there. Chemical product identification links both results to the named compound. An increase in a generic vitamin-K signal would not establish the same specific biosynthetic claim.
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