Cloning and expression of human tissue factor cDNA.

Tissue factor is a membrane protein that plays an essential role in the initiation of blood coagulation. When exposed to the circulation, tissue factor interacts with the serine protease factor VII, and the complex triggers fibrin clot formation by activating both factors IX and X of the coagulation cascade. This report describes the cloning and expression of the complementary DNA (cDNA) for human tissue factor. The cDNA encodes a protein of 263 amino acids preceded by a 32 amino acid signal peptide. The predicted protein sequence contains a potential hydrophobic membrane anchoring domain at its carboxy terminus, and bears no significant homology to any other known protein. Tissue factor mRNA of 2400 nucleotides was detected in adipose, adrenal, small intestine and a number of other tissues by Northern blot hybridization analysis. In order to confirm the identity of the cDNA, an expression vector containing the cloned cDNA was used to transfect cultured mammalian cells. These cells produced active tissue factor which was assayed using purified factors VII and X.