Fig. 3. Histone H1 binds specifically to perlecan secreted by myotubes. A total proteoglycan-enriched fraction obtained from the conditioned media of myotubes was incubated with histone H1 immobilized on nitrocellulose membranes and then eluted with 8 M urea. Total, unbound and histone-H1-bound fractions were incubated with heparitinase and separated by SDS-PAGE. Western blots were performed using (A) an anti--heparan sulfate monoclonal antibody to reveal the core proteins of heparan sulfate proteoglycans and (B) specific anti-mouse perlecan antisera, and detected by ECL. The migration of perlecan (per) and glypican (gly) are indicated on the right, and molecular weight markers on the left of each panel.