Vitamin K–dependent carboxylation of glutamate also occurs in proteins associated with bone, kidney, and regulation of cellular development and survival.
Proteins and locations
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Osteocalcin and matrix Gla protein in bone, and nephrocalcin in the kidney, undergo vitamin K–dependent carboxylation of glutamate to γ-carboxyglutamate.
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The product of the growth arrest specific gene Gas6 also undergoes this modification. It participates in regulation of differentiation and development in the nervous system and control of apoptosis in other tissues.
Calcium binding and osteocalcin
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These γ-carboxyglutamate-containing proteins bind calcium, causing a conformational change that enables interaction with membrane phospholipids.
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Release of osteocalcin into the circulation provides an index of vitamin D status.