title: Mechanism of action of vitamin K: demonstration of a liver precursor of prothrombin.
abstract: Extracts of sonicated liver microsomes that are prepared from rats deficient in vitamin K or from rats given vitamin K antagonists contain a factor that liberates a thrombin-like activity when it is incubated with venom from Echis carinatus. The amount of this factor is low in control rats and in hypoprothrombinemic rats given vitamin K 1 hour before they were killed. These data indicate that this factor is a protein precursor of prothrombin, which is synthesized in the liver.
mesh_terms: D000818:Animals; D001777:Blood Coagulation / Q000187:drug effects; D002713:Chlorine; D003513:Cycloheximide / Q000494:pharmacology; D007020:Hypoprothrombinemias / Q000378:metabolism; D008297:Male; D008862:Microsomes, Liver / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D011498:Protein Precursors / Q000032:analysis / Q000378:metabolism*; D011516:Prothrombin / Q000032:analysis / Q000096:biosynthesis*; D051381:Rats; D012911:Snakes; D014688:Venoms / Q000494:pharmacology; D014812:Vitamin K / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014859:Warfarin / Q000494:pharmacology
chemical_list: D011498:Protein Precursors; D014688:Venoms; D014812:Vitamin K; D002713:Chlorine; D014859:Warfarin; D011516:Prothrombin; D003513:Cycloheximide