Fig. 3: The inhibitory effects of MB2mP6 on Gα₁₃ interactions with β₃ integrins and on platelet function.

a Representative immunoblots (from three independent experiments) of co-immunoprecipitation of β₃ integrin and Gα₁₃ with anti-β₃ antibody in human platelets pretreated with MB2mP6 or control peptide HLPN (50 μM) for 5 min and then stimulated with thrombin (0.025 U mL⁻¹) for various lengths of time. The immunoprecipitates and total cell lysates were immunoblotted with both anti-β₃-integrin and anti-Gα₁₃ antibodies respectively. b Representative thrombin-induced human platelet aggregation tracing showing a dose-dependent inhibition of aggregation by MB2mP6 HLPN. c Representative study showing 0.03 U mL⁻¹ thrombin-induced ATP secretion in washed human platelets is dose-dependently inhibited by MB2mP6 HLPN. d Effects of MB2mP6 HLPN on thrombin-induced mouse platelet aggregation induced by increasing doses of thrombin (all groups, n = 3, independent isolated platelets). e Effects of MB2mP6 HLPN on ATP secretion from mouse platelets stimulated with increasing doses of thrombin (all groups, n = 3, independent isolated platelets). f Effects of MB2mP6 HLPN on 500 μM PAR4AP–induced binding of Oregon Green-labeled fibrinogen to mouse platelets. g Quantification of the binding of Oregon Green-labeled fibrinogen to mouse platelets induced by PAR4AP (500 μM) pretreated with MB2mP6 or scrambled peptide HLPN (all groups, n = 3, independent isolated platelets). h Lack of effect of MB2mP6 HLPN on ADP-induced mouse platelet aggregation in presence of 100 μg mL⁻¹ fibrinogen (all groups, n = 3, independent isolated platelets). i Effects of MB2mP6 HLPN on P-selectin expression in mouse platelets induced by various dose of thrombin (all groups, n = 3, independent isolated platelets). All data are shown as mean ± SEM. Data in (d), (e), (h), and (i) were analyzed by two-way ANOVA with the post hoc Sidak’s multiple comparisons test; Data in (g) was analyzed with one-way ANOVA with Tukey’s multiple comparisons test.