The use of mass spectrometry for the characterization of molecules co-purifying with integrins

Abstract

Cellular adhesion has been demonstrated to involve supramolecular complexes on plasma membranes of various cell types. These complexes involve not only transmembrane molecules, but rather extend into the cytoplasm to include signal transduction elements, adaptor proteins, and cytoskeletal components. Alterations in activation status or adhesion status of the cell lead to changes in specific associations within the complex. This dynamic process is believed to be mediated through post-translational events which modify the ability of various components to associate with or cross-link other elements. This reversible process of cellular adhesion is necessary for cellular migration through tissue. As adhesion molecules, integrins have a significant contribution to the functioning of these elaborate structures. Mass spectrometry has been used for the characterization of unidentified biomolecules, but this approach has not been utilized for analysis of supramolecular adhesion complexes. To test the validity of applying this technology to supramolecular complexes, proteins co-purifying with the integrin alpha-v/beta-3 were recovered from silver-stained SDS-PAGE gels and analyzed on a MALDI qQ-TOF. Using this approach, the protein(s) contained within each band on the gel could be identified. These findings support the use of mass spectrometry for the characterization of molecules co-purifying with integrins.