Fig. 1

Full length TF (flTF) and alternatively spliced TF (asTF) primary protein structure. flTF is an integral transmembrane protein, whereas asTF lacks a transmembrane and can be secreted. Both isoforms contain the same first 166 residues, which share an N-terminal β-sandwich and the charged lysine doublet (purple circles) necessary for FVII/FVIIa binding. Disulfide bridges are shown with green circles. Glycosylation has been reported to occur on asparagine at sites N11, N124, and N137 (red circles). flTF contains two serine residues in the C-terminus that can undergo phosphorylation (yellow circles). Palmitoylation of C243 is thought to orientate flTF in the plasma membrane. Through alternative splicing of the gene that encodes for TF, F3, a frame shift occurs and generates a unique C-terminus, resulting in the formation of asTF. asTF’s unique C-terminus contains a cluster of five positively charged residues (+) that allow asTF to interact with cell membranes