Alternative titles; symbols
HGNC Approved Gene Symbol: AWAT2
Cytogenetic location: Xq13.1 Genomic coordinates (GRCh38): X:70,040,542-70,049,938 (from NCBI)
Sebum and meibum are lipid-rich and have high percentages of wax monoesters. Wax synthases, like AWAT2, synthesize wax monoesters by conjugating a long chain fatty alcohol to a fatty acyl-CoA via an ester linkage (Cheng and Russell, 2004).
Cheng and Russell (2004) cloned mouse Awat2, which they called wax synthase. By searching a database for sequences similar to mouse Awat2, followed by PCR of an adult human skin cDNA library, they cloned human AWAT2. The mouse and human proteins both contain 333 amino acids, and they share 84% sequence identity. Real-time PCR of 20 mouse tissues detected robust expression in preputial gland and eyelid, followed by thymus, spleen, testis, skin, and heart. All other tissues showed little to no wax synthase expression. Immunohistochemical analysis revealed that epitope-tagged mouse Awat2 was expressed in the endoplasmic reticulum of transfected Chinese hamster ovary cells.
By searching databases for sequences similar to DGAT2 (606983), followed by nested PCR of a lung cDNA library, Turkish et al. (2005) cloned AWAT2, which they originally called DC4. The deduced 334-amino acid protein has a calculated molecular mass of 38.2 kD and shares 48% identity with DGAT2. AWAT2 has an N-terminal signal sequence, 2 transmembrane regions, a diacylglycerol acyltransferase (DGAT) domain, an N-glycosylation site, a potential tyrosine sulfation site, and 2 potential phosphorylation sites. Turkish et al. (2005) also cloned a splice variant of AWAT2 that lacks exon 5, resulting in a truncated protein due to the introduction of an early stop codon. Nested PCR detected AWAT2 expression in all tissues examined except placenta. In situ hybridization of human skin detected AWAT2 expression in sebaceous gland, where it was located in the cytoplasm of undifferentiated peripheral sebocytes.
Yen et al. (2005) found that full-length AWAT2, which they called MFAT, has 3 predicted transmembrane domains, an acyltransferase domain, an N-glycosylation site, 3 putative phosphorylation sites, and 3 myristoylation sites. Northern blot analysis detected major transcripts of approximately 1.5 and 2.2 kb that were expressed exclusively in skin. Quantitative PCR detected MFAT expression in lung and testis, although the mRNA levels were less than 1% of that in skin.
By assaying the membrane fraction of HEK293 cells transfected with human and mouse constructs, Cheng and Russell (2004) determined that both human and mouse AWAT2 catalyzed the formation of wax monoesters from straight-chain saturated, unsaturated, and polyunsaturated fatty alcohols and acids.
Turkish et al. (2005) showed that human AWAT2 expressed in yeast microsomes incorporated radiolabeled oleoyl-CoA into wax esters. It also more weakly incorporated radiolabeled oleate and palmitate into triglycerides. In the formation of wax esters, AWAT2 preferred C16 and C18 unsaturated alcohols over C10 saturated alcohol as acyl acceptors. AWAT2 used unsaturated as well as saturated acyl-CoAs, including C18:1, as acyl donors.
Using a wide range of acyl acceptors with palmitoyl-CoA as the acyl donor, Yen et al. (2005) found that human MFAT showed a broad range of esterification reactions in insect cells in vitro, in isolated mammalian cell membranes, and in intact cells. MFAT used monoacylglycerol, long chain alcohol, and retinol as acyl acceptor substrates to synthesize diacylglycerols, wax monoesters, and retinyl esters, respectively. Since MFAT expression was prominent in human skin, Yen et al. (2005) hypothesized that MFAT contributes to the barrier function of skin by formation of skin surface lipids and waxes.
Cheng and Russell (2004) determined that the AWAT2 gene contains 7 exons and spans approximately 8.2 kb.
By genomic sequence analysis, Cheng and Russell (2004) mapped the AWAT2 gene to chromosome Xq13.1. They mapped the mouse Awat2 gene to a region of chromosome XC3 that shares homology of synteny with human chromosome Xq13.1.
Turkish et al. (2005) reported that AWAT2 lies in a DGAT gene cluster that includes AWAT1 (300924) and DGAT2L6 (300926).
Cheng, J. B., Russell, D. W. Mammalian wax biosynthesis. II. Expression cloning of wax synthase cDNAs encoding a member of the acyltransferase enzyme family. J. Biol. Chem. 279: 37798-37807, 2004. [PubMed: 15220349] [Full Text: https://doi.org/10.1074/jbc.M406226200]
Turkish, A. R., Henneberry, A. L., Cromley, D., Padamsee, M., Oelkers, P., Bazzi, H., Christiano, A. M., Billheimer, J. T., Sturley, S. L. Identification of two novel human acyl-CoA wax alcohol acyltransferases: members of the diacylglycerol acyltransferase 2 (DGAT2) gene superfamily. J. Biol. Chem. 280: 14755-14764, 2005. [PubMed: 15671038] [Full Text: https://doi.org/10.1074/jbc.M500025200]
Yen, C.-L. E., Brown, C. H., IV, Monetti, M., Farese, R. V., Jr. A human skin multifunctional O-acyltransferase that catalyzes the synthesis of acylglycerols, waxes, and retinyl esters. J. Lipid Res. 46: 2388-2397, 2005. [PubMed: 16106050] [Full Text: https://doi.org/10.1194/jlr.M500168-JLR200]