Reaction of anti-Pg RIBS mAbs with Glu-Pg bound to substrates and regulatory molecules. Binding of RIBS mAbs (180nM) or MOPC21 isotype control (180nM) to Glu-Pg bound to a synthetic nonapeptide corresponding to the C-terminus of Pg-R_KT (A), to fibrin (B), to Pm-treated fibrinogen (C), to Matrigel (D), to mixed gangliosides (E), or binding of RIBS mAbs and MOPC21 to either K1-3 or Glu-Pg bound to a synthetic nonapeptide corresponding to the C-terminus of Pg-R_KT (F) was determined in the presence of either buffer (■, Glu-Pg + PBS) or soluble Glu-Pg (1μM; ▨, Glu-Pg + Glu-Pg) and in panel E, binding of mAbs to gelatin preincubated with Glu-Pg in the presence of either buffer (, Gelatin + Glu-Pg + PBS) or soluble Glu-Pg (▨, Gelatin + Glu-Pg + Glu-Pg). Panel F, buffer (, K1-3 + PBS) or soluble K1-3 (, K1-3 + K1-3). In controls, the substrates and regulatory molecules were not preincubated with Glu-Pg and mAb binding was determined in the absence of soluble Glu-Pg (□, PBS + PBS).