Schematic representation of the structure of TSP-1 and its receptor sites. TSP-1 is a large, homotrimeric molecule (420 kDa). Each monomer consists of an interchain disulfide bond (S=S), procollagen homology domain (PC), Type I, II, and III repeats. The amino and carboxyl terminals are globular [8]. RFK and RGDA are the binding sites for TGFβ and the integrins, respectively. CSVTCG is the receptor site for CD36. The C-terminal domain of TSP-1 binds CD47. TSP-1 mimetic peptides have been designed from the heptapeptide GVITRIR of the second type-1 repeat. ABT-526 and ABT-510 are nonapeptides and enantiomers of each other, where D-Ile was replaced with D-allo-Ile in ABT-510 [33]. Sar, Nva, and NHEt are abbreviations for sarcosine, norvaline, and ethylamide. A second generation mimetic peptide, ABT-898, has been reported to have increased potency and slower clearance [95]. These peptides have been used in clinical studies for their antiangiogenic properties. Recombinant fragment has been studied in experimental erosive arthritis [72].
