MeSH

A lipid cofactor that is required for normal blood clotting. Several forms of vitamin K have been identified: VITAMIN K 1 (phytomenadione) derived from plants, VITAMIN K 2 (menaquinone) from bacteria, and synthetic naphthoquinone provitamins, VITAMIN K 3 (menadione). Vitamin K 3 provitamins, after being alkylated in vivo, exhibit the antifibrinolytic activity of vitamin K. Green leafy vegetables, liver, cheese, butter, and egg yolk are good sources of vitamin K.

OXIDOREDUCTASES which mediate vitamin K metabolism by converting inactive vitamin K 2,3-epoxide to active vitamin K.

Year introduced: 2014 (1978)

A heterogeneous-nuclear ribonucleoprotein found in the CELL NUCLEUS and the CYTOPLASM. Heterogeneous-nuclear ribonucleoprotein K has been implicated in the regulation of gene expression at nearly all levels: GENETIC TRANSCRIPTION; mRNA processing (RNA PROCESSING, POST-TRANSCRIPTIONAL), mRNA transport, mRNA stability, and translation (TRANSLATION, GENETIC). The hnRNP protein has a strong affinity for polypyrimidine-rich RNA and for single-stranded polypyrimidine-rich DNA. Multiple hnRNP K protein isoforms exist due to alternative splicing and display different nucleic-acid-binding properties.

Year introduced: 2003

A group of substances similar to VITAMIN K 1 which contains a ring of 2-methyl-1,4-naphthoquinione and an isoprenoid side chain of varying number of isoprene units. In vitamin K 2, each isoprene unit contains a double bond. They are produced by bacteria including the normal intestinal flora.

Year introduced: 2002

A family of phylloquinones that contains a ring of 2-methyl-1,4-naphthoquinone and an isoprenoid side chain. Members of this group of vitamin K 1 have only one double bond on the proximal isoprene unit. Rich sources of vitamin K 1 include green plants, algae, and photosynthetic bacteria. Vitamin K1 has antihemorrhagic and prothrombogenic activity.

Year introduced: use PHYTONADIONE 1964-2001

An enzyme that catalyzes the hydrolysis of keratin, and of other proteins with subtilisin-like specificity. It hydrolyses peptide amides. Endopeptidase K is from the mold Tritirachium album Limber. (Enzyme Nomenclature, 1992) EC 3.4.21.64.

Year introduced: 1997

A nutritional condition produced by a deficiency of VITAMIN K in the diet, characterized by an increased tendency to hemorrhage (HEMORRHAGIC DISORDERS). Such bleeding episodes may be particularly severe in newborn infants. (From Cecil Textbook of Medicine, 19th ed, p1182)

Hemorrhage caused by vitamin K deficiency.

A cysteine protease that is highly expressed in OSTEOCLASTS and plays an essential role in BONE RESORPTION as a potent EXTRACELLULAR MATRIX-degrading enzyme.

Year introduced: 2010(1984)

An activating NK cell lectin-like receptor subfamily that regulates immune responses to INFECTION and NEOPLASMS. Members of this subfamily generally occur as homodimers.

Year introduced: 2009

A synthetic naphthoquinone without the isoprenoid side chain and biological activity, but can be converted to active vitamin K2, menaquinone, after alkylation in vivo.

Year introduced: 2002

An enzyme isolated from the GASTRIC MUCOSA that catalyzes the hydrolysis of ATP coupled with the exchange of hydrogen and potassium ions across the cell wall. This enzyme was formerly listed as EC 3.6.1.36.

Year introduced: 1994

A subclass of symporters that specifically transport POTASSIUM and CHLORIDE ions across cellular membranes. Potassium chloride cotransporters play roles in regulating cell volume and intracellular chloride concentration.

Year introduced: 2024(1989)

Family of retrovirus-associated DNA sequences (ras) originally isolated from Harvey (H-ras, Ha-ras, rasH) and Kirsten (K-ras, Ki-ras, rasK) murine sarcoma viruses. Ras genes are widely conserved among animal species and sequences corresponding to both H-ras and K-ras genes have been detected in human, avian, murine, and non-vertebrate genomes. The closely related N-ras gene has been detected in human neuroblastoma and sarcoma cell lines. All genes of the family have a similar exon-intron structure and each encodes a p21 protein.

Year introduced: 1991

A class of cell surface receptors for tachykinins that prefers neurokinin A; (NKA, substance K, neurokinin alpha, neuromedin L), neuropeptide K; (NPK); or neuropeptide gamma over other tachykinins. Neurokinin-2 (NK-2) receptors have been cloned and are similar to other G-protein coupled receptors.

Year introduced: 1994

A major class of calcium activated potassium channels whose members are voltage-dependent. MaxiK channels are activated by either membrane depolarization or an increase in intracellular Ca(2+). They are key regulators of calcium and electrical signaling in a variety of tissues.

Year introduced: 2006(2993)

metabolite from culture broth of Nocardiopsis sp.; a neurotrophin antag; inhibits BDNF TrkB receptor

Date introduced: November 5, 1986

effective in blocking formation of chemotactic factor for tumor cells from human complement; oxidized product of sesquiterpene derivative K 76 from fungus Stachybotrys complementi; do not confuse with hydroxamic acid K-76

Date introduced: September 16, 1983

Potassium channels whose activation is dependent on intracellular calcium concentrations.

Year introduced: 2002

An enzyme that catalyzes the hydrolysis of nitrophenyl phosphates to nitrophenols. At acid pH it is probably ACID PHOSPHATASE (EC 3.1.3.2); at alkaline pH it is probably ALKALINE PHOSPHATASE (EC 3.1.3.1). EC 3.1.3.41.

Year introduced: 1994