Molecular cloning of the cDNA for tissue factor, the cellular receptor for the initiation of the coagulation protease cascade

We have isolated cDNA clones encoding the complete sequence of the heavy chain of tissue factor (TF), the high-affinity receptor responsible for cellular initiation of the coagulation protease cascade. An 885 bp open reading frame encodes a 295 amino acid polypeptide including a leader sequence with alternative cleavage sites. A single 2.3 kb mRNA is identified, and Southern blotting is consistent with a single gene. The coding sequence defines a protein with features characteristic of an integral membrane protein. This receptor appears novel, lacking significant homology with other proteins; however, TF contains the uncommon tryptophan-lysine-serine (WKS) sequence repeated three times, a sequence we find in some serine protease-binding proteins and suggest may represent a functional sequence motif.