FIGURE 1.

a, DEAE-Sephacel chromatography and PG-ELISA. HSPGs were extracted from HeLa cells with TTU buffer. The extract was chromatographed over a DEAE-Sephacel column equilibrated with TTU buffer. Elution was performed by stepwise salt gradient (NaCl in TTU buffer). Eluted fractions were diluted 1:2 in water and coated on microtiter wells. Fractions were assayed for HSPG presence by an indirect ELISA using anti-CD44v3, anti-Sy-2, anti-Sy-4 antibodies or an unrelated antibody as negative control (K⁻). The data are from a representative experiment of three independent experiments. b, capture ELISA. To define which HSPG interacts with the matrix protein, specific antibodies to Sy-2, Sy-4, CD44v3, and unrelated antibody (anti-CD41) were adsorbed on microtiter plate wells. Positive and negative fractions were pooled and reacted with the four solid phases. Captured antigens were reacted with the matrix protein. Complexes were detected by MK-1 antibody and by rabbit anti-mouse IgG-HRP conjugate. Data are representative of three independent experiments.