Inhibition of factor VIIa-tissue factor coagulation activity by a hybrid protein.
Lipoprotein-associated coagulation inhibitor (LACI) appears to inhibit tissue factor (TF)-induced blood coagulation by forming a quaternary inhibitory complex containing factor Xa, LACI, factor VIIa, and TF. A genetically engineered hybrid protein consisting of the light chain of factor Xa and the first Kunitz-type inhibitor domain of LACI is shown to directly inhibit the activity of the factor VIIa-TF catalytic complex. Unlike inhibition of factor VIIa-TF activity by native LACI, inhibition by the hybrid protein is not dependent on factor Xa. In an assay of TF-induced coagulation, 50% TF inhibition occurs with hybrid protein at 35 nanograms per milliliter, whereas LACI at 2.5 micrograms per milliliter is required for an equivalent effect. gamma-Carboxylation of glutamic acid residues in the factor Xa light chain portion of the hybrid protein is required for inhibitory activity, indicating that the first Kunitz-type domain of LACI alone is not sufficient for inhibition of factor VIIa-TF.
Girard
T J
TJ
Division of Hematology/Oncology, Jewish Hospital, Washington University Medical Center, St. Louis, MO 63110.
MacPhail
L A
LA
Likert
K M
KM
Novotny
W F
WF
Miletich
J P
JP
Broze
G J
GJ
D015055:1-Carboxyglutamic Acid / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D005167:Factor VII / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D015942:Factor VIIa / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015951:Factor Xa / Q000378:metabolism / Q000494:pharmacology*; D005347:Fibroblasts / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D008074:Lipoproteins / Q000378:metabolism / Q000494:pharmacology*; D051379:Mice; D008969:Molecular Sequence Data; D027383:Papillomaviridae; D011480:Protease Inhibitors / Q000494:pharmacology*; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins / Q000494:pharmacology*; D013925:Thromboplastin / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D014162:Transfection
D005971:Glutamates; D008074:Lipoproteins; D011480:Protease Inhibitors; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; C051928:lipoprotein-associated coagulation inhibitor; D018698:Glutamic Acid; D015055:1-Carboxyglutamic Acid; D005167:Factor VII; D013925:Thromboplastin; D015942:Factor VIIa; D015951:Factor Xa; D002118:Calcium