WS/DGAT coding gene. "M. tuberculosis" has also been shown to contain 15 atf genes encoding WS/DGATs. Several of these bacterial WS/DGAT enzymes have a broad substrate range despite naturally producing a small range of wax esters. Plants Arabidopsis thaliana Scientists have also identified, characterized, and shown the WSD1 gene in Arabidopsis thaliana to encode a bifunctional wax ester synthase/diacylglycerol acyltransferase enzyme that is embedded in the ER membrane, in which the wax synthase portion is critical to wax ester synthesis using long-chain and very-long-chain primary alcohols with C fatty acids. Jojoba Although the first wax synthase in plants was identified in the jojoba plant, the jojoba wax synthase could not be functionally expressed in microorganisms like E. coli and S. cerevisiae. Animals Birds The enzyme products of genes AdWS4, TaWS4, GgWS1, GgWS2, GgWS4, and GgDGAT1 sequences have been shown to catalyze wax ester syntheses in several bird species. Mammals Scientists have discovered cDNA encoding wax synthase in the preputial gland of mice. Furthermore, it has been shown that the wax synthase gene is located on the X chromosome, the expression of which lead to the formation of wax monoesters from straight chain, saturated, unsaturated, and polyunsaturated fatty alcohols and acids and that the formation of wax esters in mammals involves a two step biosynthetic pathway involving fatty acyl-CoA reductase and wax synthase enzymes. Humans The enzymes produced by X-linked genes AWAT1 and AWAT2 have been shown to esterify long chain alcohols to produce wax esters and is most predominantly expressed in skin. Both enzymes have dissimilar substrate specificities: AWAT1 prefers decyl alcohol (C10) and AWAT2 prefers C16 and C18 alcohols while using oleoyl-CoA as the acyl donor. However, when using acetyl alcohol as the acyl acceptor, AWAT1 prefers saturated acyl groups, while AWAT2 shows activity with all four acyl-CoAs and performs two times better with unsaturated acyl-CoAs than with saturated ones. Along with the murine wax ester synthase, AWAT1 and AWAT2 are likely the most significant contributors in wax ester production in mammals. Enzyme structure While the function of the molecule has been studied, its structure has yet to be identified. Industrial relevance There is a large demand for large-scale production of cheap jojoba-like wax esters since they have multiple commercial uses. Scientists have found a way to achieve substantial biosynthesis and accumulation of neutral lipids in "E. coli", allowing for the possibilities of economic biotechnological production of cheap jojoba