for decreased transcription of the message responsible for enzyme synthesis when dietary cholesterol is high in animals: the same is observed for 3-hydroxy-3-methylglutaryl-CoA and the low density lipoprotein receptor. Bacteria In bacteria, isoprenoid precursors are generally synthesised via an alternative, non-mevalonate pathway, however a number of Gram-positive pathogens utilise a mevalonate pathway involving HMG-CoA synthase that is parallel to that found in eukaryotes. Structural studies As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes , , , and . External links References EC 2.3.3 Protein families Human proteins