Fig. 7. Processing of laminin 2 subunit by MT1-MMP. (A) Schematic representation of the heterotrimeric laminin-2, the localization of two epitopes of the antiserum and the corresponding regions of three processed fragments `a', `b' and `c' appeared in (B) and (C). Open arrow indicates a putative cutting site by MT1-MMP that generates the band `b'. Closed arrow indicates additional cleavage site that is available only in biochemical assay (discussed in Results). (B) Western blot analysis of muscle tissues obtained from 4-week-old wild type (WT) and MT1-MMP-deficient mice (MT1-MMP-/-) using anti-300K antiserum. Three arrowheads in the right indicate the major fragments detected. (C) The purified laminin-2 from human placenta was digested with the recombinant catalytic fragment of MT1-MMP (1:100, 1:50 molecular ratio in w/w) at 37°C for 18 hours. The resulting products were analyzed by western blotting, using either anti-300K or anti-IVa. Three arrowheads in the right indicate the corresponding fragments of those detected in (B).