Spatial distribution of amino acid substitutions in the protein S LG1 domain. Charged residues in the protein S LG1 domain were substituted to alanine. Four composite protein S variants were generated, each containing 4 to 6 amino acid substitutions chosen based on their spatial proximity to the sites where insertion of N-linked glycans led to a reduction in TFPI cofactor function or to amino acid residues previously suggested to be functionally important for the TFPIα enhancement. The model of the SHBG-like region is adapted from Villoutreix et al.⁴²