Thromb Haemost 2000; 84(04): 657-663
DOI: 10.1055/s-0037-1614083
Review Article
Schattauer GmbH

Tissue Factor Encryption/de-encryption Is not Altered in the Absence of the Cytoplasmic Domain

Steven D. Carson
1   From the Department of Pathology and Microbiology, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, NE
,
Michael E. Bromberg
2   Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
› Author Affiliations

This research was partially supported by grant K11-CA64205 from the National Cancer Institute and a Junior Faculty Scholar Award from the American Society of Hematology (M.E.B.), and by funds from the University of Nebraska Medical Center seed grant program (S.D.C.). Technical assistance was provided by Mr. Justin Hobbs.
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Publication History

Received 03 January 2000

Accepted after revision 14 April 2000

Publication Date:
11 December 2017 (online)

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Summary

Since the cytoplasmic domain of tissue factor (TF) appears to have a role in TF function beyond coagulation, experiments were conducted to determine whether the cytoplasmic domain also has a role in regulating procoagulant activity of TF present in the cell membrane. TF encryption was quantitated in human YU-SIT1, U87-MG, and mouse 3T3 cells which were transfected for expression of human tissue factor or a construct lacking the cytoplasmic domain (TFCD). Comparison of intact cells (encrypted) with fully disrupted cells (de-encrypted) showed that TF and TFCD were equally encrypted with respect to function in fX activation. Moreover, cells expressing TF and TFCD were indistinguishable in their procoagulant responses to A23187-calcium and varied concentrations of nonionic detergents. TF in membrane vesicles spontaneously shed by U87-MG cells was largely, but incompletely, de-encrypted, and the degree of de-encryption was independent of the cytoplasmic domain. We conclude that the predominant mechanism(s) for encrypting TF procoagulant activity is independent of the cytoplasmic domain.