Vitamin K is needed for the carboxylation of vitamin K-dependent proteins
such as osteocalcin and matrix Gla protein, while vitamin D promotes the production of vitamin K-dependent protein
Matrix GLa protein (MGP) is a vitamin K-dependent protein
that inhibits vascular and soft tissue calcification when activated.
The average American diet lacks enough vitamin K2--which is found primarily in organ meats, egg yolks, cheese, and in a Japanese staple dish of fermented soybean called natto--to properly activate those vitamin K-dependent protein
(9,19) Compounding the problem, vitamin K2 deficiency worsens with advancing age.
In 1978, the first vitamin K-dependent protein
relating to skeletal metabolism was discovered and the significance of vitamin K in bone metabolism became public at the end of the 1990s.
So do knockout mice lacking a vitamin K-dependent protein
In fact, mice that did not have the less-essential vitamin K-dependent protein
Mgp (matrix Gla protein) developed arterial and other calcifications and were dead by two months.
Researchers screened children for markers of bone health, including osteocalcin, the vitamin K-dependent protein
necessary to use calcium to build healthy bones.
In fact, MGP is classified as a vitamin K-dependent protein
because it cannot shield against calcification without adequate vitamin K.(1), (24), (25)
Protein S (PS),  a vitamin K-dependent protein
, has an important role in the natural coagulation system, as shown by the occurrence of severe thrombotic complications in neonates with homozygous PS deficiency (1,2).
Osteocalcin (OC), a vitamin K-dependent protein
expressed by osteoblasts, contains 3 gamma-carboxyglutamic acid residues derived from the vitamin K-dependent posttranslational modification of glutamic acid residues.
The physiology of vitamin K nutriture and vitamin K-dependent protein
function in atherosclerosis.
Skeletal functions of vitamin K-dependent proteins
: not just for clotting anymore.