Figure 2: Identification and characterization of the MQs. Strong cationic exchange chromatography of Dp (A) , Dj(B) and Dv (C) . Blue arrows indicate active fractions on hV2R able to inhibit more than 50% of 3H-AVP binding. (D) Binding of 3H-AVP on hV2R in the presence of MQs (colored squares, for a comparison of the complete set of toxins, see Supplementary Table 2), P19859 and Q5ZPJ7 (blue dashed lines), Dtx-I (grey dots), Dtx-K (grey squares), calcicludine (pink open circle), BPTI (light blue open circle) or five other non-active Kunitz peptides (black symbols). α-DTX, MQ2, MQ4 and MQ5 curves are not shown for clarity. (E) Toxin antagonist effect on cAMP production induced by 1.77 nM of AVP on V2R (same color code than for panel D). Dotted line corresponds to cAMP production with toxins in the absence of AVP.
Table 1: Pharmacological properties of the V2R toxins. ND: not done. The statistical significance was assessed for binding by a one-way ANOVA with post hoc test according to Dunnett in comparison to MQ1. *: p value=]0.0; 0.01]; **: p value=]0.01; 0.001]; ***: p value < 0.001 and for cAMP inhibition by t-student in comparison to MQ1 with ***: p value < 0.001. Means represent 2 to 25 independent experiments. MQ7-8: MQ7 + MQ8. Calci: calcicludine