Proteomic analysis of integrin adhesion complexes

Integrin receptors regulate cell fate by coupling the binding of extracellular adhe- sion proteins to the assembly of intracellular cytoskeletal and signaling complex- es. A detailed, integrative view of adhesion complexes will provide insight into the molecular mechanisms that control cell morphology, survival, movement, and differentiation. To date, membrane receptor–associated signaling complexes have been refractory to proteomic analysis because of their inherent lability and inaccessibility. We developed a methodology to isolate ligand-induced integrin adhesion complexes, and we used this technique to analyze the composition of complexes associated with multiple receptor–ligand pairs and define core and receptor-specific subnetworks. In particular, we identified regulator of chromo- some condensation–2 (RCC2) as a component of fibronectin-activated signaling pathways that regulate directional cell movement. The development of this pro- teomics pipeline provides the means to investigate the molecular composition and function of various adhesion complexes.