Biochemical pathway of phenoloxidase-based melanization. For a description of the pathway, see section 5.2. Abbreviations: PRR, pattern recognition receptor; βGRP, β-1,3 glucan recognition protein; CTL, C-type lectin; GNBP, Gram(−) binding protein; PPAE, phenoloxidase activating enzyme; PAH, phenylalanine hydroxylase; PO, phenoloxidase; DDC, dopa decarboxylase; DCE, dopachrome conversion enzyme.