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 γ-carboxyglutamate (Gla).

The Gla residues are responsible for the high-affinity binding of calcium ions.

[1][2] The GLA domain binds calcium ions by chelating them between two carboxylic acid residues.

This results in a conserved Gla-x(3)-Gla-x-Cys motif[3] that is found in the middle of the domain, and which seems to be important for substrate recognition by the carboxylase.

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.