Caption: Vitamin K (phylloquinone) crystals. Vitamin K (phylloquinone) is a group of 2-methilo-naphthoquinone derivatives. It is a human vitamin that is fat-soluble (lipophilic) and is needed for the posttranslational modification of certain proteins required for blood coagulation. Normally it is produced by bacteria in the intestines. Dietary deficiency is extremely rare unless the intestines are heavily damaged. Vitamin K is involved in the carboxylation of certain glutamate residues in proteins to form gamma-carboxyglutamate residues (Gla-residues). Gla-residues are usually involved in binding calcium. The Gla-residues are essential for the biological activity of all known Gla-proteins. At this time fewer than 12 human Gla-proteins have been discovered, and they play key roles in the regulation of three physiological processes. Lack of control of these processes may lead to the following: risk of uncontrolled and massive bleeding, cartilage calcification and severe malformation of developing bone, or deposition of insoluble calcium salts in the arterial vessel walls. Gla-proteins are also known to occur in a wide variety of vertebrates: mammals, birds, reptiles, and fish.
Magnification*: x25
Type: LM
Copyright 1985 Dennis Kunkel Microscopy, Inc.
Keywords: 920414-15,12.01.04,blood coagulation,calcium deposits,cartilage calcification,carboxylation,crystal,crystals,2-methilo-naphthoquinone,developing bone,gamma-carboxyglutamate residues,Gla-residues,Gla-proteins,intestine bacteria,lipophilic,naphthoquinone,Vitamin K,Vitamin K1,phylloquinone,LM