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Pathway Description
Vitamin K Metabolism
Homo sapiens
Metabolic Pathway
Created: 2013-08-01
Last Updated: 2024-11-12
Vitamin K describes a group of lipophilic, hydrophobic vitamins that exist naturally in two forms (and synthetically in three others): vitamin K1, which is found in plants, and vitamin K2, which is synthesized by bacteria. Vitamin K is an important dietary component because it is necessary as a cofacter in the activation of vitamin K dependent proteins. Metabolism of vitamin K occurs mainly in the liver. In the first step, vitamin K is reduced to its quinone form by a quinone reductase such as NAD(P)H dehydrogenase. Reduced vitamin K is the form required to convert vitamin K dependent protein precursors to their active states. It acts as a cofactor to the integral membrane enzyme vitamin K-dependent gamma-carboxylase (along with water and carbon dioxide as co-substrates), which carboxylates glutamyl residues to gamma-carboxy-glutamic acid residues on certain proteins, activating them. Each converted glutamyl residue produces a molecule of vitamin K epoxide, and certain proteins may have more than one residue requiring carboxylation. To complete the cycle, the vitamin K epoxide is returned to vitamin K via the vitamin K epoxide reductase enzyme, also an integral membrane protein. The vitamin K dependent proteins include a number of important coagulation factors, such as prothrombin. Thus, warfarin and other coumarin drugs act as anticoagulants by blocking vitamin K epoxide reductase.
References
Vitamin K Metabolism References
Litwack G. ed. Vitamins and Hormones: Vitamin K. (2008) 78. New York: Academic Press, Elsevier
Jaiswal AK: Human NAD(P)H:quinone oxidoreductase (NQO1) gene structure and induction by dioxin. Biochemistry. 1991 Nov 5;30(44):10647-53. doi: 10.1021/bi00108a007.
Pubmed: 1657151
Jaiswal AK, McBride OW, Adesnik M, Nebert DW: Human dioxin-inducible cytosolic NAD(P)H:menadione oxidoreductase. cDNA sequence and localization of gene to chromosome 16. J Biol Chem. 1988 Sep 25;263(27):13572-8.
Pubmed: 2843525
Ota T, Suzuki Y, Nishikawa T, Otsuki T, Sugiyama T, Irie R, Wakamatsu A, Hayashi K, Sato H, Nagai K, Kimura K, Makita H, Sekine M, Obayashi M, Nishi T, Shibahara T, Tanaka T, Ishii S, Yamamoto J, Saito K, Kawai Y, Isono Y, Nakamura Y, Nagahari K, Murakami K, Yasuda T, Iwayanagi T, Wagatsuma M, Shiratori A, Sudo H, Hosoiri T, Kaku Y, Kodaira H, Kondo H, Sugawara M, Takahashi M, Kanda K, Yokoi T, Furuya T, Kikkawa E, Omura Y, Abe K, Kamihara K, Katsuta N, Sato K, Tanikawa M, Yamazaki M, Ninomiya K, Ishibashi T, Yamashita H, Murakawa K, Fujimori K, Tanai H, Kimata M, Watanabe M, Hiraoka S, Chiba Y, Ishida S, Ono Y, Takiguchi S, Watanabe S, Yosida M, Hotuta T, Kusano J, Kanehori K, Takahashi-Fujii A, Hara H, Tanase TO, Nomura Y, Togiya S, Komai F, Hara R, Takeuchi K, Arita M, Imose N, Musashino K, Yuuki H, Oshima A, Sasaki N, Aotsuka S, Yoshikawa Y, Matsunawa H, Ichihara T, Shiohata N, Sano S, Moriya S, Momiyama H, Satoh N, Takami S, Terashima Y, Suzuki O, Nakagawa S, Senoh A, Mizoguchi H, Goto Y, Shimizu F, Wakebe H, Hishigaki H, Watanabe T, Sugiyama A, Takemoto M, Kawakami B, Yamazaki M, Watanabe K, Kumagai A, Itakura S, Fukuzumi Y, Fujimori Y, Komiyama M, Tashiro H, Tanigami A, Fujiwara T, Ono T, Yamada K, Fujii Y, Ozaki K, Hirao M, Ohmori Y, Kawabata A, Hikiji T, Kobatake N, Inagaki H, Ikema Y, Okamoto S, Okitani R, Kawakami T, Noguchi S, Itoh T, Shigeta K, Senba T, Matsumura K, Nakajima Y, Mizuno T, Morinaga M, Sasaki M, Togashi T, Oyama M, Hata H, Watanabe M, Komatsu T, Mizushima-Sugano J, Satoh T, Shirai Y, Takahashi Y, Nakagawa K, Okumura K, Nagase T, Nomura N, Kikuchi H, Masuho Y, Yamashita R, Nakai K, Yada T, Nakamura Y, Ohara O, Isogai T, Sugano S: Complete sequencing and characterization of 21,243 full-length human cDNAs. Nat Genet. 2004 Jan;36(1):40-5. doi: 10.1038/ng1285. Epub 2003 Dec 21.
Pubmed: 14702039
Wu SM, Cheung WF, Frazier D, Stafford DW: Cloning and expression of the cDNA for human gamma-glutamyl carboxylase. Science. 1991 Dec 13;254(5038):1634-6. doi: 10.1126/science.1749935.
Pubmed: 1749935
Wu SM, Stafford DW, Frazier LD, Fu YY, High KA, Chu K, Sanchez-Vega B, Solera J: Genomic sequence and transcription start site for the human gamma-glutamyl carboxylase. Blood. 1997 Jun 1;89(11):4058-62.
Pubmed: 9166845
Rost S, Fregin A, Ivaskevicius V, Conzelmann E, Hortnagel K, Pelz HJ, Lappegard K, Seifried E, Scharrer I, Tuddenham EG, Muller CR, Strom TM, Oldenburg J: Mutations in VKORC1 cause warfarin resistance and multiple coagulation factor deficiency type 2. Nature. 2004 Feb 5;427(6974):537-41. doi: 10.1038/nature02214.
Pubmed: 14765194
Watzka M, Geisen C, Bevans CG, Sittinger K, Spohn G, Rost S, Seifried E, Muller CR, Oldenburg J: Thirteen novel VKORC1 mutations associated with oral anticoagulant resistance: insights into improved patient diagnosis and treatment. J Thromb Haemost. 2011 Jan;9(1):109-18. doi: 10.1111/j.1538-7836.2010.04095.x.
Pubmed: 20946155
Li T, Chang CY, Jin DY, Lin PJ, Khvorova A, Stafford DW: Identification of the gene for vitamin K epoxide reductase. Nature. 2004 Feb 5;427(6974):541-4. doi: 10.1038/nature02254.
Pubmed: 14765195
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