Structure of the Ca2+-free GLA domain sheds light on membrane binding of blood coagulation proteins

Abstract

Reversible membrane binding of gamma-carboxyglutamic acid (Gla)-containing coagulation factors requires Ca(2+)-binding to 10-12 Gla residues. Here we describe the solution structure of the Ca(2+)-free Gla-EGF domain pair of factor x which reveals a striking difference between the Ca(2+)-free and Ca(2+)-loaded forms. In the Ca(2+)-free form Gla residues are exposed to solvent and Phe 4, Leu 5 and Val 8 form a hydrophobic cluster in the interior of the domain. In the Ca(2+)-loaded form Gla residues ligate Ca2+ in the core of the domain pushing the side-chains of the three hydrophobic residues into the solvent. We propose that the Ca(2+)-induced exposure of hydrophobic side chains is crucial for membrane binding of Gla-containing coagulation proteins.

Localization of the specific binding site for magnesium(II) ions in factor IX

“…(2) Insertion of glycine as the fourth residue occurs in factor IX. (3) A cluster of three hydrophobic residues followed by a basic residue (in human factor X, FLyyVK, residues 4~9), which constitute the putative binding site for phospholipids [16], is well conserved in this family but, in factor IX, it is changed to KLwF.._y_v in the human and bovine proteins. It is thus possible that these residues unique to factor IX act as ligands for a Mg 2+ ion, though we cannot exclude possibility of the participation of the C-terminal portion, where some difference is also found.…”

Stress signaling from the lumen of the endoplasmic reticulum: coordination of gene transcriptional and translational controls

“…CHOP was originally identified as a gene induced on DNA damage and growth arrest (Fornace et al 1988). However, subsequent studies have demonstrated a strong correlation between development of ER stress and induction of CHOP (Bartlett et al 1992;Chen et al 1992;Sunnerhagen et al 1995;Carlberg et al 1996;Brewer et al 1997;Dricu et al 1997). CHOP induction closely parallels the time course of BiP induction, where maximal induction occurs after several hours.…”

Site‐directed mutagenesis but not γ‐carboxylation of Glu‐35 in factor VIIa affects the association with tissue factor

“…The N-terminal domain, encoded on a separate exon, contains the first 37 amino acid residues including all 10 y-carboxyglutamic acid (Gla) residues [2]. This so-called Gla domain binds seven Ca r+ ions [3,4], an event mediated by the Gla residues, and thereby attains a membrane-interactive ability through the exposure of hydrophobic side chains [4,5]. Studies of the roles of the individual Gla residues in factor IX [6], protein C [7][8][9][10] and prothrombin [11], all of which are homologous to fVII, have been conducted.…”