The vitamin K-dependent proteins: an update.

Historically known for its role in blood coagulation, vitamin K also has been shown to be required for the physiologic activation of numerous proteins that are not involved in hemostasis. Over the last 20 years, vitamin K-dependent proteins have been isolated in bone, cartilage, kidney, atheromatous plaque, and numerous soft tissues. Although the precise mechanism of action of many of these proteins remains to be determined, their discovery has proven important from a physiologic point of view.