A number of methyltransferases have been shown to share regions ofsimilarities []. Apart from the ubiquinone/menaquinone biosynthesis methyltransferases (for example, the C-methyltransferase from the ubiE gene of Escherichia coli), the ubiquinone biosynthesis methyltransferases (for example, the C-methyltransferase from the COQ5 gene of Saccharomyces cerevisiae) and the menaquinone biosynthesis methyltransferases (for example, the C-methyltransferase from the MENH gene of Bacillus subtilis), this family also includes methyltransferases involved in biotin and sterol biosynthesis and in phosphatidylethanolamine methylation.