Fig. 4

SDS-PAGE and immunoblotting of aggrecan with antibodies to different regions. Proteoglycan from guanidine extracts of OA articular cartilage, treated with keratanase and chondroitinase ABC, was analyzed by electrophoresis on polyacrylamide gels, and the fractionated proteoglycan then transferred to nitrocellulose membranes. Aggrecan was visualized by immunoblotting using antibodies recognizing the G1, G2, CS1 or G3 regions. Cartilage samples were obtained adjacent to the lesion (L), midway between the lesion and the joint margin (M), and remote from the lesion (R) from the femoral condyles. Representative samples from patient 1 are shown. Molecular weights of reference proteins are indicated at the left hand side of the blot. Schematic diagrams depicting the core protein structure of aggrecan fragments of different sizes are included at the right side of the blot