Integrin Activation. Intracellular signaling converts an integrin aß heterodimer from an inactive, bent conformation to an active conformation that can bind ligands. Several molecules, including Rap1 and talin, have been implicated in the formation of a complex that binds to NXXY/F motifs within the cytoplasmic tail of the ß subunit during inside-out signaling. The role of kindlin-3 in integrin activation is unknown. However, it has also recently been shown to bind to NXXY/F motifs.3