TSP-1 and TSP-2 fragments.

(A) The subgroup A thrombospondins, TSP-1 and TSP-2, share a similar molecular architecture comprising a unique heparin-binding domain at the N-terminus followed by a connecting region that links 3 subunits via interchain disulfide bonds, a procollagenlike module, 3 properdinlike or type 1 modules, 3 EGF-like or type 2 modules, 7 type-3 repeats (12 unique calcium-binding loops), and a unique C-terminal sequence. The NoC-1 fragment contains the connecting region and is trimeric. The residue numbers are for the mature proteins. TSP-1 begins at Asn1, while TSP-2 begins at Gly1. (B) SDS-PAGE profile of the TSP-1 and TSP-2 fragments. Samples (4 μg) of TSP-1 (lane 1) and the TSP-1 (lanes 2-6) and TSP-2 (lanes 7 and 8) fragments were resolved on 8% to 16% SDS-PAGE under reducing conditions and stained with Coomassie blue. The positions of M_r markers are shown at left.