Thromb Haemost 1989; 62(02): 699-703
DOI: 10.1055/s-0038-1646886
Original Article
Schattauer GmbH Stuttgart

Single-Chain and Two-Chain Tissue-Type Plasminogen Activator (t-PA) Bind Differently to Cultured Human Endothelial Cells

Authors

  • Rob J Aerts

    The Department of Molecular Biology, Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, Amsterdam, The Netherlands
  • Karin Gillis

    The Department of Molecular Biology, Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, Amsterdam, The Netherlands
  • Hans Pannekoek

    The Department of Molecular Biology, Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, Amsterdam, The Netherlands
Further Information

Publication History

Received 07 February 1989

Accepted after revision 06 April 1989

Publication Date:
30 June 2018 (online)

Preview

Summary

It has recently been shown that the fibrinolytic components plasminogen and tissue-type plasminogen activator (t-PA) both bind to cultured human umbilical vein endothelial cells (HUVEC). After cleavage of t-PA by plasmin, “single-chain” t-PA (sct-PA) is converted into “two-chain” t-PA (tct-PA), which differs from the former in a number of respects. We compared binding of sct-PA and tct-PA to the surface of HUVEC. Removal of t-PA bound to HUVEC by a mild treatment with acid and a subsequent quantification of eluted t-PA both by activity- and immunoradiometric assays revealed that, at concentrations between 10 and 500 nM, HUVEC bind about 3-4 times more sct-PA than tct-PA. At these concentrations, both sct-PA and tct-PA remain active when bound to HUVEC. Mutual competition experiments showed that sct-PA and tct-PA can virtually fully inhibit binding of each other to HUVEC, but that an about twofold higher concentration of tct-PA is required to prevent halfmaximal binding of sct-PA than visa versa. These results demonstrate that sct-PA and tct-PA bind with different affinities to the same binding sites on HUVEC.