Vitamin K-dependent carboxylation/gamma-carboxyglutamic (GLA) domain is a protein domain that contains post-translational modifications of many glutamate residues by vitamin K-dependent carboxylation to form gamma-carboxyglutamate (Gla). The Gla residues are responsible for the high-affinity binding of calcium ions [1][2].
The GLA domain is responsible for the high-affinity binding of calcium ions. It starts at the N-terminal extremity of the mature form of proteins and ends with a conserved aromatic residue; a conserved Gla-x(3)-Gla-x-Cys motif[3] is found in the middle of the domain which seems to be important for substrate recognition by the carboxylase.
The 3D structures of several Gla domains have been solved[4][5]. Calcium ions induce conformational changes in the Gla domain and are necessary for the Gla domain to fold properly. A common structural feature of functional Gla domains is the clustering of N-terminal hydrophobic residues into a hydrophobic patch that mediates interaction with the cell surface membrane[5].
^ Vermeer C (1990). "Gamma-carboxyglutamate-containing proteins and the vitamin K-dependent carboxylase". Biochem. J.266 (3): 625–636. PMID 2183788.
^ Price PA, Fraser JD, Metz-Virca G (1987). "Molecular cloning of matrix Gla protein: implications for substrate recognition by the vitamin K-dependent gamma-carboxylase". Proc. Natl. Acad. Sci. U.S.A.84 (23): 8335–8339. doi:10.1073/pnas.84.23.8335. PMID 3317405.
^ Freedman SJ, Furie BC, Furie B, Baleja JD (1995). "Structure of the metal-free gamma-carboxyglutamic acid-rich membrane binding region of factor IX by two-dimensional NMR spectroscopy". J. Biol. Chem.270 (14): 7980–7987. doi:10.1074/jbc.270.14.7980. PMID 7713897.
^ ab Freedman SJ, Furie BC, Furie B, Baleja JD, Blostein MD, Jacobs M (1996). "Identification of the phospholipid binding site in the vitamin K-dependent blood coagulation protein factor IX". J. Biol. Chem.271 (27): 16227–16236. doi:10.1074/jbc.271.27.16227. PMID 8663165.