Identification of important residues on FLCE for species-specific egg envelope digestion. The activities of rLCEs towards the medaka mid-ZPd peptide are shown in the order of steps 1 (A), 2 (B), 3 (C), and 4 (D) (see text). Circles, triangles, and crosses indicate complete, partial, and no solubilization of the swollen medaka egg envelope, respectively. (E) Km values (μM) of rLCEs towards medaka or Fundulus peptides. Bars represent “not determined”. (F) The morphology of unchanged, partially solubilized, or solubilized swollen envelope. Scale bars, 100 μm.