A prenyltransferase is an enzyme that transfers a prenyl group, an isoprenoid-derived carbon group, to an acceptor. The term covers multiple reactions; the acceptor can be a small molecule rather than a protein. It should therefore not be interpreted as meaning only an enzyme for protein prenylation.
One concrete reaction joins the five-carbon dimethylallyl diphosphate and five-carbon isopentenyl diphosphate to make ten-carbon geranyl diphosphate, releasing diphosphate. Carbon counting gives , while the substrate names specify the activated donors and the product structure. The official entry for this enzyme also notes poor acceptance of larger prenyl diphosphates as donors: a generic transfer label does not imply unrestricted substrate choice.[ref]
A different example links this chemistry to Vitamin K. In 2010, Kimie Nakagawa and colleagues identified UBIAD1 as an enzyme for menaquinone-4 biosynthesis. Reducing its expression suppressed conversion of deuterium-labelled vitamin-K derivatives into labelled product; expression in insect cells restored a production system, and nuclear magnetic resonance helped identify the product.[ref]
Identification of UBIAD1 as a novel human menaquinone-4 biosynthetic enzyme by Kimie Nakagawa and others. Abstract, gene suppression, expression and product identification
Combining perturbation with chemical identification provides stronger evidence for an enzyme assignment than finding a similar-looking gene sequence alone. New to topics? Read the docs here!