The role of 14-3-3 in GPIb-IX signaling. (A) VWF binding and shear force–induced, GPIb-mediated mechanosensing and 14-3-3ζ–dependent GPIb-IX signaling pathways. (i) VWF binding to GPIb-IX in a conformation with folded MSD and LRRs. (ii) Pulling force generated by shear stress induces unfolding of LRR and MSD, converting mechanical signal into GPIb conformational changes in the membrane-proximal/spanning domain, which induces a 14-3-3–dependent signaling cascade leading to granule secretion and integrin activation. (B) Cooperative signaling between GPIb-IX and protease-activated receptors (PARs) dependent on 14-3-3 (adapted from Estevez et al¹⁴⁶ ). Thrombin cleavage of PAR1 or PAR4 and binding to GPIb-IX induces 14-3-3–dependent cooperative signaling between GPIb-IX and PARs, enabling platelet response to low thrombin concentrations. cGMP, cyclic guanidine monophosphate; ITAM, immunoreceptor tyrosine-based activation motif; LIMK1, LIM kinase 1; NO, nitric oxide; PI3K, phosphatidylinositol 3-kinase; PKC, protein kinase C; PKG, cGMP-dependent protein kinase; TXA2, thromboxane A2.