Integrin receptor signaling: the propagation of an alpha-helix model.

Upon ligand binding to integrin receptors, a transmembrane conformation change occurs, which is required for the engagement of the actin cytoskeleton. Integrin receptor latency clearly involves the proximal portions of the alpha and beta cytoplasmic domains. Several experiments suggest that these two regions, which are highly conserved among integrins, may be associated, and this association is the structural basis for latency. We propose that ligand binding leads to a disruption of this association, which allows for the folding of the proximal beta cytoplasmic domain. Thus, in this model, the alpha chain association keeps the beta unfolded, and ligand binding leads to the propagation of an alpha helix from the transmembrane domain through the proximal beta cytoplasmic domain, leading to signal transduction.