Amino acid found in blood coagulation proteins (prothrombin, Factor VII, Factor IX, Factor X, q.q.v.), plasma proteins and proteins from calcified tissue. Presence of Gla confers metal binding properties to the protein. Discovery in prothrombin: J. Stenflo, Proc. Natl. Acad. Sci. USA 71, 2730 (1974); G. L. Nelsestuen et al., J. Biol. Chem. 249, 6347 (1974). Synthesis: S. Danishefsky et al., J. Am. Chem. Soc. 101, 4385 (1979); of dl-form: H. R. Morris et al., Biochem. Biophys. Res. Commun. 62, 856 (1975); W. M"arki, R. Schwyzer, Helv. Chim. Acta 58, 1471 (1975); B. Weinstein et al., J. Org. Chem. 41, 3634 (1976). Resolution of d- and l-forms: W. M"arki et al., Helv. Chim. Acta 60, 798 (1977). Biosynthesis by vitamin K-dependent carboxylation of glutamic acid: C. T. Esmon et al., J. Biol. Chem. 250, 4744 (1975). Metal binding properties: G. L. Nelsestuen et al., Biochem. Biophys. Res. Commun. 65, 233 (1975); G. L. Nelsestuen, J. Biol. Chem. 251, 5648 (1976); R. Robertson et al., ibid. 253, 5880 (1978); S. P. Bajaj et al., ibid. 257, 3726 (1982). HPLC determn in proteins, bone, urine: M. Kuwada, K. Katayama, Anal. Biochem. 117, 259 (1981). Reviews: J. Stenflo, J. W. Suttie, Annu. Rev. Biochem. 46, 157-172 (1977); R. E. Olson, J. W. Suttie, Vitam. Horm. 35, 59-108 (1977); J. W. Suttie, Crit. Rev. Biochem. 8, 191-223 (1980); J. P. Burnier et al., Mol. Cell. Biochem. 39, 191-207 (1981).