Human Thrombospondin‑1 Biotinylated Antibody

Thrombospondin-1 (TSP-1) is a 150‑180 kDa charter member of the thrombospondin family of extracellular matrix proteins. Human TSP‑1 is synthesized as an 1170 amino acid (aa) precursor that contains an 18 aa signal sequence and 1152 aa mature molecule. The mature molecule has been described as containing three distinct regions that create the shape of a dumbbell. There is an intital, 140 aa N-terminal laminin G-like globular region that binds heparin (aa 19‑258). This is followed by an extended, central collagen-binding region that contains one type C von Willebrand factor domain, plus three TSP type I and three TSP type II (or EGF-like) domains (aa 259‑712). The C‑terminus (aa 713‑1170) appears as a large globule with two halves; one calcium‑binding region (aa 713‑950) with seven Asp‑rich TSP type III domains, and one terminal region (aa 951‑1170) with TSP‑unique motifs (1). This C-terminal region is believed to mediate CD47 and cell binding (2‑5). The TSP type I repeats have multiple functions. They bind to type V collagen, laminin, fibronectin and CD36. They also contain a recognition site for C‑mannosylation on Trp. Finally, a type I KRFK motif induces the release of mature TGF-beta from LAP. This is an effect not found in TSP-2. The function of the type II repeats in unclear. TSP‑1 is secreted as a disulfide-linked 450 kDa homotrimer. The cysteines responsible lie just N‑terminal to the first type I TSP repeat. Mature human TSP-1 is 61% aa identical to human TSP-2. It is also 95%, 97% and 95% aa identical to mouse, dog and rat TSP-1, respectively.