The homotrimeric TSP-1 activates latent TGFβ1 by binding the N-terminal propeptide LAP and the mature TGFβ1. The binding results in conformational changes in TGFβ1 and allows TGFβ1 to be recognized by its receptor. Mature, active TGFβ1 has been reported to decrease dendritic cell maturation and activate T cells. An opposing role of TGFβ1 results in fibrosis.
