Human Fibroblast Activation Protein  alpha /FAP Alexa Fluor™ Plus 405‑conjugated Antibody

FAP (also known as Seprase) is a 97 kDa Type II transmembrane serine protease that is structurally related to Dipeptidyl Peptidase IV (DPPIV) (1). FAP has substrate specificity similar to DPPIV, which is specific for N-terminal Xaa-Pro sequences, but FAP is also an endopeptidase able to degrade gelatin and Type I Collagen (2). The enzymatically active form of FAP is a dimer that migrates at ~170 kDa. It is associated with multiple integral membrane proteins such as Integrin  alpha ₃ beta ₁, UPA and DPPIV (3,4). FAP has a restricted tissue distribution. It is occasionally detected in fibroblasts and pancreatic islet cells, but is highly expressed on reactive stromal fibroblasts in epithelial cancers, in granulation tissue during wound healing, and in bone and soft tissue sarcomas (4-6). Because of its expression patterns and enzymatic activities, FAP is believed to play roles in tumor invasion, tissue remodeling, and wound repair. The 760 amino acid (aa) human FAP contains a 735 aa extracellular domain that is glycosylated and necessary for activity (4). It shares 90% aa identity with mouse and rat FAP. A reported 672 aa splicing variant diverges prior to the active site charge relay residues at the C-terminus.