FIGURE 5.

A peptide containing the internal region of LRR6 decorin competes with full-length decorin for binding to LRP-1 and reduces LRP-1-mediated decorin endocytosis. A, sequence of peptides from the LRR6 region of decorin, LRR6 (Full), LRR6i (In), and LRR6e (Ext), are depicted and their potential locations in the three-dimensional decorin molecule are shown based on the structural model described by Scott et al. (44). B, C2C12 myoblasts were incubated with 75 nm hDcnHA at 4 °C for 3 h in the absence or presence of 225 nm of the synthetic peptides derived from LRR6 as described in A, cell extracts were immunoprecipitated with anti-LRP-1 antibody and the presence of hDcnHA and LRP-1 in the immunoprecipitate were evaluated by Western blot using anti-HA and anti-LRP-1 antibodies, respectively. C, C2C12 myoblasts were incubated with ³⁵S-decorin mutants at 37 °C for 3 h in the absence or presence of synthetic peptides from the LRR6 region of decorin as described in A and B, or scramble peptide. The cells were then analyzed to determinate decorin endocytosis levels as described in the legend to Fig. 1C. Values correspond to the mean ± S.D. from three independent experiments (* and #, p < 0.001).