Thrombospondin

Thrombospondin (TSP ) are secreted proteins that inhibit the growth of small blood vessels ( angiogenesis).

Importance

The thrombospondins are a family of proteins which are involved in different biological processes. For this reason, thrombospondin are known as multifunctional proteins. The protein family consists of thrombospondin 1-5. We distinguish subgroups: the subgroup A consists of TSP1 and TSP2; the subgroup B consists of TSP3, TSP4 and TSP5. TSP1 and TSP2 are homotrimers, that is, they consist of three identical subunits. TSP3, TSP4 and TSP5 are homopentameric, they consist of five identical subunits.

TSP1 first of platelets (thrombocytes) isolated, stimulated with thrombin. For this reason, thrombospondin was initially referred to as ' thrombin - sensitive protein '. TSP1 is involved in many different biological processes such as the formation of new blood vessels (angiogenesis ), programmed cell death (apoptosis ), the activation of TGF- β Gewebshormons and immune regulation. TSP1 has several receptors, including CD36, CD47 and integrins.

TSP2 also inhibits angiogenesis and is involved in cell adhesion, cell migration ( cell migration ) and the proliferation involved.

In the development of the brain TSP1 and TSP2 formed by immature astrocytes. This promotes the formation of new synapses.