|Protein Name||S-adenosylmethionine synthase|
|Milk Fraction||MFGM, Exosome|
|Ref Sequence ID||NP_001094601.1|
|Protein Existence Status||Unreviewed: Experimental evidence at protein level|
|Presence in other biological fluids/tissue/cells||expressed in human liver, red blood cells, rat liver, heat, kidney and brain|
|Protein Function||Synthesizes SAM (S-adenosylmethionine), the principle methyl group donor and precursor for polyamine and glutathione synthesis; catalyses the transfer of the adenosyl group from ATP to the sulfur atom of Met (Lmethionine), in an unusual two-step reaction cleaving at both ends of the ATP triphosphate chain|
|Biochemical Properties||25 mM cycloleucine, a known competitive inhibitor of Sadenosylmethionine synthetases; as found in red blood cells, the enzyme has a high affinity for methionine; enzyme is only fully activated at total Mg2+ concentrations manyfold higher than the ATP concentration; at near physiological levels of ATP (1 mM), maximal activity is obtained at or above 20 mM MgCl2; the pH optimum of the human erythrocyte enzyme is 5.2; regulatory properties of this enzyme appear to be pH dependent; rat liver is strikingly stimulated by Me2SO at a low concentration; the enzyme activities in the cytosol from rat brain, heart, and kidney are reported to be slightly inhibited by Me2SO; pH optima for the activity of rat liver and kidney 5-Ado-Met synthetases were broad between pH 7.5 and 9.5; liver enzymes and the kidney enzyme absolutely required Mg2+ and K+ for the activity|
|Significance in milk||involved in metheonine supply in milk- methionine supply has a potential biological impact within mammary tissue|
| Site(s) of PTM(s) |
|Bibliography||1. Okada, G., Teraoka, H., & Tsukada, K. (1981). Multiple species of mammalian S-adenosylmethionine synthetase. Partial purification and characterization. Biochemistry, 20(4), 934–940. https://doi.org/10.1021/bi00507a045. |
2. Shafqat, N., Muniz, J. R. C., Pilka, E. S., Papagrigoriou, E., von Delft, F., Oppermann, U., & Yue, W. W. (2013). Insight into S-adenosylmethionine biosynthesis from the crystal structures of the human methionine adenosyltransferase catalytic and regulatory subunits. The Biochemical Journal, 452(1), 27–36. https://doi.org/10.1042/BJ20121580.
3. Oden, K. L., & Clarke, S. (1983). S-adenosyl-L-methionine synthetase from human erythrocytes: role in the regulation of cellular S-adenosylmethionine levels. Biochemistry, 22(12), 2978–2986. https://doi.org/10.1021/bi00281a030.
4. Han, L., Batistel, F., Ma, Y., Alharthi, A. S. M., Parys, C., & Loor, J. J. (2018). Methionine supply alters mammary gland antioxidant gene networks via phosphorylation of nuclear factor erythroid 2-like 2 (NFE2L2) protein in dairy cows during the periparturient period. Journal of Dairy Science, 101(9), 8505–8512. https://doi.org/10.3168/jds.2017-14206.
5. Taylor, J. C., Bock, C. W., Takusagawa, F., & Markham, G. D. (2009). Discovery of novel types of inhibitors of S-adenosylmethionine synthesis by virtual screening. Journal of Medicinal Chemistry, 52(19), 5967–5973. https://doi.org/10.1021/jm9006142.